Battle of Atlantic , Black May - Michael Gannon

The U.S. Navy might well be grateful that it was not worse than it was, which one may assume it would have been if Donitz had been allotted the twelve boats he sought for the opening blow; and had Hitler not in February diverted twenty operational boats to reconnaissance duty off the coast of Norway, where he expected imminent British landings; and had not a particularly severe European winter frozen the Southern Baltic parts where scores of new boats were trapped while working up;’ and had not thirteen boats, including the now much-sought-after Type IXs, been lost in the ill-starred attempt to stop North Africa-bound convoys in the vicinity of Gibraltar.

If there were any consolations that the Allies could draw from the massacre on the American Main, it would seem that they were three in number: First, it occurred at just the time when the new Kriegsmarine four-rotor cipher Triton came into service fleet-wide, and as a result, except for three days, 23 and 24 February and 14 March, GC&CS went blind for eleven months. For the Allies to possess Enigma information during the period February-July would have granted them no special advantage, since the majority of U-boats, operating independently and transmitting infrequently, could not have been located regularly by cryptographic intelligence; nor could shipping have been diverted around them on the strength of Sigint. Of course, when the U-boat offensive returned to midocean convoy routes starting in August, and radio-directed patrol lines began forming again, the absence of Enigma was keenly felt.

Even then, Commander Winn’s Tracking Room was not without resources, which included access to the Heimische Gewässer (Home Waters) key, which continued to be used by the Kriegsmarine for Räumboot (motor minesweeper) escorts that shepherded U-boats in and out of the Biscay bases; penetration of the Tetis key used by new boats working up in the Baltic; RFP, or radio fingerprinting, which could identify an individual U-boat’s transmitter; TINA, an oscillographic operator signature device that displayed the specific keying style, or “fist,” of each U-boat Morse sender; HF/DF; and knowledge long assembled in the Tracking Room about BdU’s operating theory, characteristics of particular Commanders, U-boat routes, average speed of advance, and endurance at sea. From these remaining sources, plus Winn’s canny intuition, the Tracking Room developed daily an estimate, or “working fiction,” of U-boat operations.

The second consolation, to British strategists as much as to any like-minded officers in the USN, was the convincing demonstration in American waters of the value of convoy as a battle-winning expedient. And why was it so? Because either (I) the convoy drew U-boats to warships: instead of fruitlessly searching for the elusive craft—“hunting the hornets all over the farm”—the escorts had the U-boats in close proximity, where they could be attacked; or (2) the U-boats, unnerved by the hazards of attacking protected shipping, withdrew to more congenial waters, as happened in the American experience; or (3) attack opportunities declined mathematically, since if a U-boat was not correctly positioned to attack a convoy, it missed all the ships that formed it, and had to wait a long while for another chance.

The third consolation that the Allies could take from the first half of 1942 was that the sea war in the west bought time for RAF Coastal Command and RN escorts to enlarge forces, improve training, and perfect tactics. It is to that opportunity, and to the role of the boffins, that our narrative now turns.

When in June 1941 Air Marshal Philip Joubert de la Ferté took command at Northwood, succeeding Air Chief Marshal Frederick Bowhill as Air Officer Commanding in Chief (AOC-in-C) RAF Coastal Command, he decided that he needed an advisor at his elbow in the operations room who was not a member of the uniformed service: a civilian scientist, privy to every operation and every command secret, who could give him objective, disinterested guidance on the day-by-day anti-U-boat war. In Joubert’s radical concept this civilian would advise on matters normally understood as being exclusively within the province of the RAF officer. His choice fell on Patrick M. S. Blackett, one of the most accomplished and versatile physicists of his day— “wonderfully intelligent, charming, fun to be with, dignified and handsome … married to one of the most delightful women in the world who did much to prevent him from becoming too serious.” An Royal Navy veteran of World War I, Blackett had given scientific advice to the Air Ministry during the mid-1930s when serving as a member of the shortlived “Tizard Committee,” chaired by physicist Henry Tizard. Other members of that body, which was largely responsible for the initiation of Britain’s radar network, were physiologist A. V. Hill and physicists H. E. Wimperis, A. P. Rowe, and F. A. Lindemann, later Lord Cherwell. This was a prototype “Operational Research Section,” a term that radar pioneer Watson Watt would later claim to have coined in 1940.

With Lindemann, whose presence on the Tizard committee was owed to pressure exerted by the then Mr. Winston Churchill, Blackett had a difficult relationship up to and throughout the war. In 1939–1940 Blackett worked with the Royal Aircraft Establishment (R.A.E.) at Farnborough, where he designed bombsights and other equipment that he personally flight-tested. With physicist Evan James Williams (1903–1945), whom he recruited to Farnborough, he worked on magnetic field detection of submarines. Blackett served seven months in 1940–1941 at the Anti-Aircraft (A.A.) Command at Stanmore, where he worked on gun-laying radar sets, until March 1941, when he received the call from Joubert.

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Professor Patrick Blackett , later honored as Baron Blackett for his wartime services to Crown

Taking Williams with him, Blackett made it clear to Joubert that he had severed all connections to the design, manufacture, and testing of weapons. “From the first,” he wrote later, “I refused to be drawn into technical midwifery.” Instead, he would hold himself free for nonroutine investigations of a purely scientific nature; he would encourage numerical thinking on the conduct of operations; he would subject every assumption to quantitative analysis and empirical test; and thus he would “help to avoid running the war on gusts of emotion.” He rejected, too, the constant clamor of all the services for “new weapons for old.” What was needed at Coastal, he concluded, was for commanders, air crews, and maintenance personnel to make “proper use of what we have got.”

To that end he and Williams began scrutinizing every aspect of Coastal’s operations and asking or recognizing the importance of questions about even the blindingly obvious. To give an example: There had to be measurable explanations for what was then Coastal’s very low U-boat sighting rate and mere 1 percent kill rate of those boats sighted. A month after assuming his new position, Blackett paid a visit to Admiral Percy Noble’s Royal Navy Western Approaches operations room at Derby House, Liverpool, from which all British surface and air escorts were controlled; indeed, it should be pointed out that since March 1941, Coastal, while remaining an essential arm of the RAF, had been under the operational command of the Admiralty, the two services sharing responsibility for the air war against U-boats. The positions of escorts as well as the estimated positions of U-boats were displayed on an immense wall plot. A quick glance at Coastal Command aircraft positions and examination of their numbers of hours flown led Blackett to calculate on the back of an envelope the number of U-boats that should be sighted by the aircraft. Back at Northwood he checked actual sightings for that day and found them to be four times fewer than what he had calculated.

The reason eluded him until one day a Wing Commander asked casually, “What color are our aircraft?” Blackett recognized at once that that was the right question. RAF Coastal Command bombers, designed originally for night action over land, were painted black—a paint that made them stand out starkly against a North Atlantic cerulean blue or overcast sky, thus enabling an observant U-boat to dive before being sighted. Using first models and then aircraft, Blackett found that a white-painted bomber was sighted at 20 percent less distance than that at which a black aircraft was seen. Williams then calculated that a white aircraft would sight a surfaced U-boat on 30 percent more occasions than a black one, which should lead to an increase in sinkings. Within a few months all Coastal aircraft used on anti-U-boat patrols were repainted with matte white leading edges and under-surfaces.

A less simple problem, and one that became a classic in the early history of operations research, was that of depth charge (D/C) settings. The prevailing assumption at Coastal Command and the Admiralty was that on average, U-boats that sighted approaching aircraft could dive to a depth of about 100 feet before an attack could be delivered. Accordingly, depth charges were set to explode at that depth. The reasoning seemed flawless until Williams discovered (1) that if a boat had gotten that deep, it would also have traveled a certain distance horizontally, with the result that a bomber would not know where to drop his D/Cs; and (2) that in about 40 percent of attacks to date the boat was on the surface or had been submerged for no longer than 15 seconds, in which case 100-foot fuse settings rendered the D/Cs useless.

After some difficulty on Williams’s part in persuading Coastal officers that if the depth-setting adjuster was turned down to the 25-foot mark, the average number of U-boats sunk per given number of attacks would increase by two and a half times, the shallower setting was gradually introduced, starting with 50 feet in July 1941, progressing to 33 feet in January 1942, and reaching 25 feet in July of that year. The changes in setting were accompanied by a corresponding increase in lethality. Commented Blackett: “There can be few cases where such a great operational gain had been obtained by such a small and simple change of tactics.”

Under Blackett the Operational Research Section (O.R.S.) at Coastal grew into a tightly knit and formidable band of scholars, which included two future Nobel Prize winners (Blackett and John C. Kendrew), five future Fellows of the Royal Society (Blackett, Kendrew, Williams, C. H. Waddington, G. W. Robertson), and one future Fellow of the National Academy of Sciences of Australia (J. M. Rendel). With the exception of Blackett, who was forty-five in 1942, all were in their twenties and thirties. These and other O.R.S. members took on a wide range of problems affecting Coastal’s performance. Nine times out of ten the O.R.S. analysis found that existing operational assumptions and procedures were soundly based. Joubert’s staff had concluded, for example, that it was a better tactic to force a U-boat pack’s convoy shadower under the surface and thus disrupt the pack’s operation while it was being organized than to wait until after an attack was made to intervene.

O.R.S. analysis was able to confirm and refine this tactic by showing that in order to do this, patrols must not be laid on too close to the convoy’s position. Studies had found, ironically, that most U-boat sightings had been made by aircraft that failed to meet their convoys. This led to the conclusion that most of a U-boat pack assembled more than twenty miles distant from the threatened convoy, and air patrols were vectored accordingly. During the period August 1942-May 1943, patrol at a distance yielded 40 percent more air attacks than continuous close escort (which was the American doctrine), greatly reduced sinkings by day, halved losses on the first night of a convoy battle and halved them again on the second, and detected a high density of boats behind the convoy, indicating that the work of the shadower had been frustrated and that the cohesion of the pack had been unhinged.

Blackett undertook additional studies of depth charge attacks (later continued by Dr. E. C. Baughan), which, like the 25-foot D/C setting, led to considerable improvement in lethality. Although Coastal personnel engaged in much discussion about bomb weight, some proposing D/Cs of 35, 100, or 600 pounds, Blackett was convinced that the current 250-pound weapon, with its 19–20 foot killing range, was perfectly serviceable if it was used correctly. He investigated its use under two categories: (1) aiming accuracy and (2) stick spacing. (A stick was a group of four to eight individual D/Cs dropped either all together as a salvo or, more often, in a series. In a series drop, an electromechanical intervalometer was used to establish the distance between the D/Cs, that is, “stick spacing.” The overall length of the D/C string was the “stick length.”)

For accuracy studies Blackett had a rear-facing mirror camera fitted to bombers and examined what the attack photographs showed, which was that pilots were placing the center of the stick length at a point 60 yards ahead of a surfaced U-boat’s conning tower. When asked why, pilots told him that it was “aim-off” to allow for the forward travel of the boat during the interval when the D/Cs were falling. This was in the manual; it was how they had been trained. But the photographs showed that the aim-off was not working. Blackett advised Joubert to have the pilots aim bang-on at the conning tower, even though it seemed to violate common sense. When they started doing so, kills increased by 50 percent.

The optimum stick spacing was a more complex problem, the resolution of which was not reached until after Blackett’s departure from Coastal Command in January 1942. Current practice of pilots was to set for 36 feet between charges, but mathematical analysis suggested that this was too short. The O.R.S. recommendation that the spacing be increased to 100 feet was accepted by the Coastal staff in March 1943, after which straddles of a U-boat with 100-foot spacing were increasingly lethal.

O.R.S. attacked many other problems, some as mundane as what came to be called Planned Flying and Maintenance, pursued by Dr. C. E. Gordon, whose aim was to make maximum possible use of crewmen and aircraft. Gordon found that in a typical squadron of nineteen aircraft only 6 percent of the time (in hours) was spent in the air; 23 percent on the ground even though crews were available and aircraft were operational; 30 percent in repair or maintenance; and 41 percent waiting on spare parts or manpower. If efficient use could be made of Coastal’s already existing resources, the force at sea could be greatly enlarged. Gordon’s “efficiency study,” as one would call it today, led to a near doubling of flying hours—a squadron of nineteen increasing from 1,300 to 4,000 hours—and proportionately greater peril to U-boats. The O.R.S. system was eventually adopted throughout the RAF and the Naval Air Division.

Other O.R.S. members, particularly the mathematicians, worked on more arcane problems, such as aircraft operational sweep rate and width; sighting ranges of various aircraft and of the various sighting positions within an aircraft; optimum altitudes for visual and radar searches; eye rest requirements for crew; probability-of-kill-given-sighting; open water navigation technique; the average number of convoys sighted by a U-boat during its lifetime (seven and a half), the average life expectancy of a U-boat (14 patrols), and development of what today would be called a “macro-model” of U-boat circulation in the North Atlantic. In January 1942, as earlier noted, Blackett left Coastal Command. His place as Officer in Charge was taken by Professor Williams. The section’s work continued as before, with what might be called even closer association of uniformed Command and civilian scientist after 6 February 1943, when Air Marshal Sir John Slessor succeeded Joubert as AOC-in-C of RAF Coastal Command.

Waddington testified that “At least in the sphere of my experience, I have rarely met such critical generosity of mind as was shown to us civilian ‘intruders.’” At no time, it appears, was there the slightest concern on the part of Joubert or Slessor that the “suck it and see” scientists sought an unwarranted prominence for themselves or ever considered themselves as anything other than members of a team.

In citing the contributions to Coastal of non-RAF personnel, special mention should be made of the senior Naval Liaison Officer, Commander, later Captain, D. V. Peyton Ward, R.N., who was the very embodiment of the close and fruitful relationship that existed between Coastal Command and the Admiralty. An invalided-out submariner, “P.W.,” as he was affectionately known at Northwood, volunteered for tasks not normally required of his position, and after Joubert’s arrival he took it upon himself to interview all returning aircrews who had sighted and/or sunk a U-boat. By writing up and analyzing each such incident, he greatly enlarged the attack data available to O.R.S. A navy-blue in the midst of RAF slate-blue, he represented Coastal Command on the important interservice U-Boat Assessment Committee, which judged the success of surface and air attacks. After the war, he wrote the official four-volume history of air operations in the maritime war. All the while O.R.S. and P.W. were bending their minds, the aircrews practiced their own difficult art of air search, hundreds of miles out over the Atlantic’s gray flannel, noisily patrolling 1,000 to 5,000 feet off the deck, in every kind of weather, dirty and cold, rarely if ever in their entire flight careers sighting a single U-boat to reward them for their protracted and boring hours. Said one crewman:

“It is difficult to describe the intense boredom of the sorties we undertook: hour after hour after hour with nothing to look at but sea. I am sure that when they found U-boats many crews pressed home their attacks regardless of what was being thrown at them, merely because it was a welcome relief from the boredom.”

And many crews would be shot down, in distant positions where no assistance was near or possible. And many other crews were lost to the sea not through enemy action, but through engine failure, adverse weather, navigational error, and fuel depletion.

Coastal Command’s motto was: “Constant Endeavor.”

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The Bay of Biscay is a roughly triangular body of water bordering the Atlantic that is formed on the north by the Brittany peninsula of France, where it does an arabesque toward Land’s End on England’s Cornwall coast, and on the south by the northern provinces of Spain. About 86,000 square miles (223,000 square kilometers) in size, and 15,525 feet (4,735 meters) deep at its center, it was the body of water traversed by U-boats operating out of bases at the western French ports of Brest, Lorient, St.-Nazaire, La Pallice, and Bordeaux. Normally, outbound and inbound boats transited through a zone, or “choke point,” about 300 miles north to south and 200 miles east to west. Here, more than at any other sea position, U-boats could be found in high concentration: traffic ranged from forty-five boats per month in June 1942 to a figure that, in early 1943, passed 100 (expected to increase to 150 by spring). The Strait of Gibraltar was another choke point, but far fewer boats attempted its passage; and the northern route from Germany around the north of Scotland was another transit area, but one that was used almost exclusively by new boats coming into Atlantic service. If one wanted to find a large number of U-boats bunched up in any one place, it would be in the transit zone of the Bay of Biscay.33 In March 1943, the Admiralty said of the enemy:

“Apart from modifying his tactics, or disengaging from an attack, he can withdraw altogether from any given convoy area as he had done to a large extent in the areas off the American coast. He cannot withdraw from the Bay.”

Whether U-boats were bound to and from the midocean transatlantic convoy lanes, where the most intensive pack battles were fought, or to and from what the British called the Outer Seas—Freetown, Cape Town, the Indian Ocean, the Atlantic Narrows, Brazil, the Caribbean, and the North American seaboard—the swept channels of the Biscay minefields were the narrow funnel through which every boat had to pass. To an adversary with marksman instincts, the Bay presented an irresistible bull’s-eye.

From the date he assumed command at Northwood in 1941, Air Chief Marshal Joubert cast a malevolent glare in that direction. Like many at Coastal before him, he could not understand why Bomber Command with its heavy bombardment squadrons had not destroyed the steel and concrete U-boat bunkers while they were still under construction and vulnerable. As a matter of fact, Bomber Command did attempt to disrupt construction, making twenty nighttime raids on the Lorient base in 1940, sixteen in 1941, and twelve in early 1942. The U.S. Eighth Air Force made ten daylight raids on St.-Nazaire between November 1942 and June 1943. Other raids were mounted against Brest. All such raids were ineffectual, owing to poor bombing accuracy and to intense anti-aircraft fire that caused heavy bomber losses. The only result on the ground was the flattening of the towns where the bases were situated. Of Lorient and St.-Nazaire, Admiral Donitz said that not a cat or a dog survived. Left with the problem of nearly completed bomb shelters, Joubert decided that since Coastal Command was envisioned to be an offensive instrument and the hunter role suited his nature, he would direct as much of its power as he could spare from convoy escort to that of offensive patrol against U-boats transiting the Bay. In making that decision, he entered a debate that would never be completely resolved, either in Coastal or the Admiralty: whether ‘tis nobler to defend convoys and so win the Atlantic by seeing merchantmen to safe and timely arrivals at their destinations, or to take up arms against a sea of U-boats, and by hunting, kill them?

What came to be called the First Bay Offensive, launched by Joubert in the summer of 1941, was a daytime operation flown by RAF Coastal Command Sunderlands, Wellingtons, Whitleys, Hudsons, and Catalinas, all of them equipped with 1.5-meter wavelength ASV Mark II radar. It yielded very disappointing results. O.R.S. analysts discovered that 60 percent of the U-boats sighted the approaching aircraft before being spotted themselves, and thus were able to dive out of harm’s way. As the campaign wore on into autumn, it became clear that transiting U-boat commanders, alerted to the increased presence of aircraft in the Bay, were charging their batteries on the surface at night and traveling as much as possible submerged during the day. Sightings of boats decreased accordingly, and the record shows that the year ended without a single U-boat kill by aircraft in the Bay.

What was needed, argued Professor Blackett of O.R.S., who chaired a specially organized Night Attack Sub-Committee under the ASW Committee on Aircraft Attacks in the Admiralty, was an effective means of delivering attacks during darkness when the U-boats were on the surface charging. And that meant an illuminant that could display to the pilot’s eye targets detected first by radar. In early 1942 combat experiments were run using 4-inch flares towed by radar-equipped Whitleys, but these proved unsuccessful. Another, more promising illuminant was waiting in the wings.

When in September 1940 the then AOC-in-C Air Chief Marshal Bowhill sent around a memorandum asking officers and airmen to submit ideas for improvement of ASW operations, he received back a detailed proposal for an airborne searchlight for use in night attacks on surfaced U-boats. It came from a nontechnical source, a World War I pilot who had flown ASW patrols over the Mediterranean in that conflict, named Squadron Leader Humphrey de Verde “Sammy” Leigh, now serving as Assistant Personnel Officer in headquarters administration. Leigh proposed that the so-called DWI Wellingtons, which had earlier, but no longer, been used to explode magnetic mines from the air by generating a powerful electrical charge, be refitted with a belly-installed retractable carbon arc lamp. The DWIs recommended themselves for this use because they were already equipped with auxiliary engines and either 35-or 90-kilowatt generators.

Bowhill was so impressed by the idea that he relieved Leigh of his desk duties and set him to work full-time on the project. There were numerous obstacles to overcome, starting with the technicians at RAE, Farnborough, who argued the case for towed flares as preferable to the searchlight scheme. The nontechnician Leigh pressed on regardless, and ingeniously solved every problem that he encountered, among them ventilation of the carbon arc fumes, steering control of the lamp’s beam in azimuth and elevation, prevention of back glare, or “dazzle,” and reduction of weight. In March 1941 the Vickers plant at Brook-lands completed a prototype installation employing a naval 24-inch (61 cm) narrow-beam searchlight, giving a maximum 50 million candles without a spreading lens, powered by seven 12-volt 40-ampere-hour type D accumulators (storage batteries); and on the night of 4 May, with Leigh himself operating the light controls in the nose, the first Leigh Light Wellington repeatedly detected, illuminated, and “attacked” the British submarine H—31 off Northern Ireland. Bowhill was no less gratified at this success than Leigh, but only one month later, when Bowhill was relieved by Joubert, the whole project was canceled and Leigh found himself reassigned to a desk.

It happened that Joubert had been associated with the development of a competing airborne light system called the Helmore Light, after an RAF Group Captain, which had been designed for illuminating enemy bombers at night, and the new AOC-in-C thought it should be used against U-boats as well. But the Helmore Light was quickly shown to be unsuitable for Coastal work: its massive array of accumulators occupied the entire bomb bay; the light could not be steered, or aimed, except by moving the entire aircraft; and the brightness of the light, which was mounted in the nose, dazzled both the operator and the pilot. “After some two months I found, as I do not mind admitting,” Joubert wrote later, “that I had made a mistake.” Leigh cleaned out his desk a second time and returned to the hangar.

Months of redesign, flight testing, crew training, and what Peyton Ward called “difficult to explain” administrative delays followed, until finally, at the beginning of June 1942, a “penny packet” of five Leigh Light (L/L) Wellingtons of No. 172 Squadron entered operational service in the Bay. The first L/L-assisted attack was made on 4 June against the Italian submarine Luigi Torelli (Tenente di Vascello [Lt.-Cmdr.] Augusto Migliorini), resulting in severe damage. The attack was made by Squadron Leader Jeaff Greswell, flying Wellington “F” of 172 Squadron. During June and July the Wellington bombers, showing what the surprised and helpless Germans came to call das verdammte Licht— “that damn light”—made altogether eleven sightings and six attacks, resulting in one kill—the Type IXC U-502 (Kptlt. Jürgen von Rosenstiel) en route home from the Caribbean, sunk by Wellington VIII “H” flown by Pilot Officer Wiley Howell, an American serving with the RAF—and two boats damaged.

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Leigh Light mounted on a Sunderland flying boat

Before the Wellingtons could improve on that record, Admiral Donitz ordered his U-boats in the Bay: “Because the danger of attacks without warning from radar-equipped aircraft is [now] greater by night than by day, in future U-boats are to surface by day…. ” In a month and a half’s time the Leigh Light had taken the night away from U-boats in the Bay, but that, it turned out, would be for now their major contribution. The air war in the Bay returned to daylight hours, and with slightly better returns than before, as between mid-July and the end of September, conventionally equipped aircraft made over seventy sightings and sank three additional U-boats.

Still, the great opportunity that the Bay presented eluded Coastal’ Commands grasp. The ratio of kills to daytime sightings remained disappointingly low throughout the remainder of 1942 and well into the new year. Whereas Coastal Command had expected that with increased time given to practice attacks, with, at last, 25-foot depth pistols, and with Torpex fillings, the percentage of lethal attacks would rise to 20 percent, it hovered instead at 6 percent. The lethality problem prevailed everywhere in waters that the U-boats infested, even where attacks were made from unseen cloud approaches on Class A targets, that is, those in which the U-boat was on the surface or had been submerged fewer than 15 seconds. Coastal was divided on the question of where blame should be placed: on poor weapons or on poor aim? Rear gunner reports and photographs suggested that the 250-pound Torpex D/C did not seem to injure boats even when perfect straddles were achieved. The O.R.S., however, defended the weapon, and, after intense study, determined that, photographs seemingly to the contrary, the problem was aiming, which could be corrected by more and better training.

In support of this conclusion the O.R.S. produced evidence that three outstanding squadrons, No. 120 (6 kills, 10 damaged), No. 202 (4 kills, 5 damaged), and No. 500 (4 kills, 9 damaged) also had solid records in practice bombing. It pointed as well to certain individual pilots, such as Squadron Leader Terence M. Bulloch, of No. 120 Squadron, with three U-boats sunk and three damaged, and Flying Officer M. A. “Mike” Ensor of No. 500, with one U-boat sunk and three damaged. In each case, the former in a Liberator, the latter in a Hudson, painstaking practice had translated into successful performance in combat. There was nothing wrong with the weapon. O.R.S.'s findings set in train intensive drills in marksmanship.

Another problem that the daylight bombers had to face was an increase in opposition from the Luftwaffe, which in the summer and fall of 1942 attempted to interdict Coastal Command patrols in the Bay, employing Focke-Wulf 190s, Heinkel 115s, Junkers 88s, Messerschmitt 210s, and Arado 196 fighter patrols to cover U-Boat routes on the Bay. Some aircraft and crew casualties resulted, but No. 235 Beaufighter Squadron at Chivenor in Devon successfully fought the attackers off, and the enemy air effort died away.

The nighttime bombers, which continued busy in the Bay Offensive, had problems of their own. The first was the French tunny (tuna) fleet, which followed the shoals of tunny into the middle Bay where most of the Leigh Light aircraft were operating. Numerous A.S.V. blips, when illuminated, turned out to be tunny craft. Their radar signature was indistinguishable from that of a U-boat. Use of the searchlight in these cases not only caused a 25 percent waste of effort and ran down the electrical power in the batteries, it gave fair warning to U-boats nearby that an L/L Wellington was in the area. In August the problem was so severe that L/L missions were considered futile and Coastal attempted to warn off the fishing craft by BBC broadcasts, leaflets, and threats to shoot, but nothing worked and the interference remained intractable until the end of the tunny season in October.

In the meantime the L/L flights, indeed all flights, were confronted by a far more serious problem. Admiral Dönitz’s technical staff had concluded, correctly, that the illuminated attacks in the Bay had been made possible by airborne metric radar. Helped by an A.S.V. Mark II set captured in Tunisia, BdU technicians developed a radar receiver (Type R.600) that could detect the presence of 1.5-meter pulses and give a U-boat time to dive out of danger. In fact, it produced a warning signal at a greater range than that at which an aircraft could acquire the blip (plus or minus 10 miles). Manufactured by the Paris firm Metox (also later by Grandin), the equipment was put to sea in August on three boats, U—214, U—107, and U—69. Except for problems encountered with the antenna, which was affixed to a crude wooden crosspiece (Biskayakreuz, the “Biscay cross,” as it came to be called) that had to be carried up and down the tower ladder when surfacing and diving, causing troublesome delays, the three boats reported favorably on the device’s effectiveness. Donitz then ordered the equipment fitted to every boat in the fleet, a process that was nearly complete by the end of the year. This logical German countermeasure enabled the boats to resume surfacing by night.

A dramatic falloff in Coastal Command sightings, both day and night, together with intelligence drawn by Winn and Beesly from naval Enigma, gave Northwood a strong clue to what had happened. The value of the Bay campaign in these circumstances came under strong questioning, and AOC-in-C Joubert pressed London hard for 10-centimeter equipment with which to defeat the German Search Receiver (G.S.R.). But the first squadron to be so equipped did not become operational until the following March 1943. In the meantime, Coastal relied on the only expedient available: flooding. In this tactic all the aircraft over the Bay except the L/L Wellingtons, which, it was hoped, might catch a U-boat off its guard, were to use their A.S.V. continuously. The expectation was that with the G.S.R. alarm ringing without stop, U-boats would not know when they were being targeted—an alarm that rang all the time was as useless as one that rang not at all—and so might become complacent or careless. But the tactic did not lead to additional sightings and attacks. In fact, during January 1943 a total of 3,136 day hours led to only five sightings, and 827 hours of combined L/L and conventional night patrols produced only three sightings. These were a new low record in the Bay.

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During the U-boats’ six-month-long picnic on the North American seaboard, overstretched and weary RN surface escorts had a respite in which to fit new detection gear, practice use of weapons, including, on some ships, the new Hedgehog, and train ranks and ratings. The ratings’ first training experience, and in many cases, their first glimpse of the sea came when newly commissioned escort vessels received their working up at HMS Western Isles in Tobermory harbor on the Isle of Mull off the west coast of Scotland. There the legendary (and quirky) Commodore Gilbert “Puggy” (or “Monkey”) Stephenson took callow “Hostilities Only” landlubbers—1,132 groups in all during the war— and, within two to three weeks’ time, shaped them into disciplined, semiskilled seamen who went directly into convoy escort service.

‘While Stephenson’s work with new crews did not require a respite from combat to carry on, the efficiency training of Captains and Watch-Keeping Officers did. This was particularly true of the Western Approaches Tactical Unit (WATU), an operational ASW analysis facility established at the suggestion of Churchill in January 1942, coincidentally the beginning month of the U-boats’ American campaign. The facility was erected on the bomb-damaged top floor of the Tate and Lyle Exchange Buildings to the east of Commander-in-Chief Western Approaches (CinCWA) in Derby House, Liverpool. To organize and direct the WATU, Churchill sent an RN Commander (later Captain) named Gilbert Howlands Roberts who, like Peyton Ward at Northwood, had been invalided out of the Navy, in his case because of tuberculosis.

A former destroyer Captain who was trained as a gunnery officer, Roberts modeled his facility on the floor plot used at gunnery school. He divided off a large linoleum-covered floor representing the open sea with lines ten inches apart indicating miles, and placed on that “Tactical Table” wooden models of convoy ships, escort vessels, and U-boats. Then, with canvas and string, he screened off any view of the ocean except for small apertures that gave only restricted views of an operational situation, akin to the restrictions prevailing at sea, particularly at night. Twenty-four “players” could work at the full floor plot, or three groups of eight players each could work at partitions of the plot. They sat at plotting tables around the viewscreens.

While a staff mainly of seventeen-to twenty-year-old Wrens (Women’s Royal Naval Service, or WRNS) manipulated both the models and the views allowed of them, combat situations were simulated and escort group Captains and Watch-Keeping Officers were asked to make decisions about appropriate actions to take in the circumstances shown—the circumstances being based on intensive interviews Roberts had conducted with Senior Officers of Escort Groups. Every movement was tracked, those of the U-boats in green chalk, those of the escorts in white, so that at the conclusion of “The Game,” as the exercise was called, the participants could inspect their successes and failures in pursuit and attack. The tactical course lasted six days, and as the months progressed, the teenage Wrens gained sufficient competence to be able, discreetly, to advise sea-hardened officers on what might be their next best course of action—as remembered by a Lieutenant (later novelist) named Nicholas Monsarrat, who allowed in his The Cruel Sea, “Rather unfairly they seemed to know all about everything…. ”

Numerous innovative attack procedures evolved from these exercises, the first of them based on reports of U-boat attack behavior during the passage of Convoy HG.76 from Gibraltar to the U.K. in December 1941 that were given Roberts by an offensive-minded Senior Officer Escort (SO) named Commander (later Captain) Frederic John Walker, who commanded the convoy’s Escort Group 36. Whereas Walker’s escorts thought that a U-boat that attacked HG.76 was about a mile outside the convoy, Roberts deduced from a simulation on his plot that the boat attacked from within the convoy columns, having infiltrated from astern. He thereupon devised a countermeasure to catch such a boat as it attempted escape. Since one of the Wrens suggested that the new tactic would give a “raspberry” to Hitler, Roberts assigned it that name. CinCWA Admiral Noble informed Churchill of this correction to “a cardinal error in anti-U-boat tactics” and within twenty-four hours signaled instructions for Raspberry to the Fleet.43 This tactic and a modification called Half-Raspberry were the first universally prescribed escort counterattack maneuvers; prior to their decree each SO was free to devise his own maneuvers. Soon, after trials on the Tactical Table, other fruit-named tactics were developed: “Pineapple,” “Gooseberry,” and “Strawberry”; to be joined by “Beta Search,” “Artichoke,” and “Observant.” Meanwhile, sea training in these maneuvers went on at Londonderry, Greenock, Birkenhead, Freetown, Bombay, St. John’s, Newfoundland, and Sydney, Nova Scotia, where escort groups practiced as teams under their own SOs.

It was these finely honed escort teams who met the U-boat men when the latter returned in force to the mid-Atlantic in early August, 1942. The slugging match between these two old enemies from that date until the start of May 1943 was fierce and relentless, but, as already indicated in this chapter and in the prologue, neither side was able to deliver a knockout blow. Nor was the renewed German effort against convoys limited to the major transatlantic trade routes. Admiral Donitz probed for soft spots in the Outer Seas where Allied defenses might have been attenuated by the need to reinforce the northern lanes; thus, he deployed boats to Freetown, Cape Town, and Madagascar, to the Atlantic Narrows between West Africa and Brazil, to the Brazilian and Panamanian coasts, and to the traffic area eastward of Trinidad in the Caribbean.

In raw numbers the U-boats enjoyed commendable successes. During August, with 86 boats at sea, the U-Bootwaffe made an impressive number of convoy contacts per boat and sank 105 ships for 517,295 GRT; and in November, as noted earlier, the boats scored their highest monthly total of tonnage sunk in the entire Atlantic war. But throughout the period August 1942 to April 1943, their ever-increasing number of operational boats at sea generated diminishing returns in tonnage sunk per boat per day at sea—this despite the fact that U-tankers in midocean were multiplying their days at sea, deferring their maintenance, alleviating operational delays caused by the backlog of boats needing fuel at base, and frustrating Coastal Command’s Bay Offensive by eliminating the need for two transits per boat through the Bay. (In the twelvemonth period prior to the end of May 1943 the supply U-boats replenished 220 U-boats operating against Atlantic convoys as well as 170 boats assigned to Outer Seas.

All the while, the experience and proficiency levels of the U-boat crews were declining, owing both to losses and to rapid expansion, while those of the escort crews were waxing, thanks in great part to the intense training regimen of January-July 1942, and to the fitting during the same period of new equipment such as HF/DF and 10-centimeter radar. From August through April 1943 the U-boats were being sunk at a monthly rate of 9.7, including February’s record 19. In the same period, three out of four ocean convoys made port without loss and 90 percent of those convoys that were attacked similarly reached their destinations. German intelligence and BdU completely missed the military convoys of the Anglo-American expeditionary force (Operation Torch) that sailed from the U.K. and the U.S. beginning on 18 October and effected landings on 8 November in French Northwest Africa, at Casablanca in Morocco, and at Oran and Algiers in Algeria. Only one of the 334 ships that participated was attacked by a U-boat, and it by accidental encounter. German records do not disclose a single sighting, even inkling, of that armada as such.

CERTAIN TITLES FOR TRADE AND MILITARY CONVOYS
CU New York-CuraCao-United Kingdom.
GU Alexandria-North Africa-U.S.A.
HG Gibraltar-United Kingdom.
HX Halifax-United Kingdom.
KMF United Kingdom-North Africa-Port Said (Fast).
KMS United Kingdom-North Africa-Port Said (Slow).
KX United Kingdom-Gibraltar (Special).
MKF Mediterranean-North Africa-United Kingdom (Fast).
MKS Mediterranean-North Africa-United Kingdom (Slow).
OG United Kingdom-Gibraltar.
ON United Kingdom-North America.
ONS United Kingdom-North America.
OS United Kingdom-West Africa.
SC Halifax-United Kingdom (Slow).
SL Sierra Leone-United Kingdom.
UC United Kingdom-Curaçao-New York.
UG U.S. A.-North Africa.
UGF U.S.A.-North Africa.
UGS U.S.A.-North Africa.
UT U.S.A.-United Kingdom (Military).
WS United Kingdom-Middle East and India (Military).
XK Gibraltar-United Kingdom (Special).
EC Southend to Clyde, Oban or Loch Ewe (Coastal Convoys, North about).
WN Clyde, Oban or Loch Ewe to Methil (Coastal Convoys, North about).

Donitz, who had expected a possible Allied action at Dakar, and had stationed boats in the Freetown and Cape Verde Island zones as a precaution, found himself on 8 November completely out of position. His rushed disposition of boats to the Moroccan Atlantic coast and to the western approaches of Gibraltar to attack new supply shipping and thus strangle the invasion buildup led to the sinking of ten merchant ships, four transports, and five warships—including Werner Henke’s fleet repair ship HMS Hecla on n/12 November—but at terrible cost: eight U-boats sunk, 19 damaged, and one Italian submarine sunk. With such thin results attended by disproportionately high losses, Donitz pulled his boats in early December for assignment to more productive areas of the Atlantic.

Three notable command changes took place in the fall and winter of 1942–1943. On 17 November 1942, Admiral Sir Max Horton, since December 1939 Vice-Admiral (later Admiral) Submarines, succeeded Percy Noble as CinCWA (Commander in Chief Westertn Approaches Command Royal Navy). Noble was named Chief of the British Admiralty delegation (BAD) in Washington. Horton had earlier turned down C-in-C Home Fleet because he thought that post to be too much under the thumb of Whitehall. At Submarine Command in Northways, Hampstead, he had forged close working ties with Coastal Command at nearby Northwood, and during three years of war became convinced “that fleets cannot operate without the close cooperation of air power”—a conviction that he would translate into deeds at Western Approaches.

Upon his arrival at the large gray block of buildings that was Derby House, he inspected its facilities, including the armored and gasproof Operations Room in its basement, and called for the principal officers to explain their duties. To Gilbert Roberts of the Tactical School he said, “What do you think you do?” Roberts replied, “Why don’t you come up and see properly?” Horton did, and at 9:00 the next morning he returned unattended to begin the six-day course. Not everyone so impressed Horton, however, and more than a few officers fell victim to deadwood cutting.

Admiral Max Horton

Admiral Max Horton , Commander in Chief of Wesrtern Approaches Command after 17 November 1942 and winner of Battle of Atlantic (it is amusing that everyone knows the losing side’s leader Donitz since he published his Memoirs after the war when he was reeleased from prison in 1956 but Horton who won the Battle of Atlantic remained unknown since he did not publish his memoirs before his untimely death in 1951)

Horton’s mandate as CinCWA was: “the protection of trade, the routing and control of all convoys and measures to combat any attack on convoy by U-boats or hostile aircraft within his Command.” (Military convoys and fast troopships remained under the control of the Admiralty.) He also saw as his responsibility the improvement and intensification of training. Early in February 1943 he received a yacht, HMS Philante, and a submarine, sometimes two, with which, in effect, to take Roberts’s Tactical School to sea. At Larne in Northern Ireland each Escort Group prior to joining its convoy was put through exercises designed by Captain A. J. Baker-Creswell, R.N., to represent actual combat conditions to be encountered. What was more, the exercises were conducted in close cooperation with Coastal Command aircraft, in order to perfect navigation and rendezvous, TBS and signal code communications, and joint attack procedures. Furthermore, surface-air collaboration was to be practiced even while with the convoys en route. And the surface Escort Groups, a Percy Noble innovation, were to be kept together as teams.

Another Noble innovation that, except for one prototype, had not been possible to implement in his predecessor’s time for lack of assets was Support Groups—small, highly trained, and offensively minded flotillas of destroyers, sloops, frigates, and cutters that would ride to the rescue of convoys and Escort Groups directly menaced or under attack. In Noble’s vision such groups would include, when they became available, auxiliary aircraft carriers. Horton embraced the concept and wrote almost daily to the Admiralty begging for ships to make the forces possible, eventually succeeding in obtaining the loan of a number of Home Fleet destroyers. To these he took the risk of adding sixteen warships obtained by reducing the strength of each Escort Group by one vessel. The result was, at the end of March, five Support Groups fully trained and ready to fulfill their sole mission: hunt down and kill U-boats.

Meanwhile, in his glass-fronted office facing the Operations Room, Horton had constant access in an adjoining office to Air Vice Marshal Sir Leonard H. Slatter, commanding No. 15 Group, whose squadrons covered the North Atlantic convoy lanes from bases on the West Coast of Scotland, in the Hebrides, and in Northern Ireland, with a detachment at Reykjavik. Both men lived on the premises, though Slatter did not follow Horton’s somewhat eccentric daily schedule, which had him on the golf course all afternoon, at the bridge table after dinner, and in his office by 2330, usually in “worn and split” pajamas, drinking barley water while directing convoy battles on the huge wall plot opposite, and with, as one observer said, an “uncanny prevision” of what the U-boats would do next. Different in manner from the urbane and kindly Noble, for whom everyone at Derby House had affection as well as respect, especially the Wrens, Horton’s behavior prompted such descriptions as “ruthless,” “determined,” “selfish,” “intolerant,” “perfectionist,” and “maddening.” Apparently the flinty old submariner was just the type Churchill thought should lead the surface and air escorts into the dangerous new year—“a thief to catch a thief,” as it were.

The second major command change affected that other thief, Karl Dönitz at BdU. When in December Adolf Hitler harangued Grossadmiral Erich Raeder, Commander-in-Chief Navy (Oberbefehlshaber der Kriegsmarine), over the failure of a surface force led by two heavy cruisers to advance successfully against an RN Arctic convoy escort screen, and went on to threaten the scrapping of all big ships in the fleet, the proud Hamburger veteran of the Imperial Navy and Battle of Jutland tendered his resignation, which the Führer, though surprised, accepted. On 30 January 1943 Dönitz was named Grossadmiral and C-in-C in his stead, while retaining his command as Flag Officer U-Boats. Now Dönitz had direct access to Hitler, whom he could importune for steel and shipyard workers; he had authority over the Naval Staff, Seekriegsleitung (Skl), whose approvals he need no longer seek; and he had freedom to prosecute the Tonnageschlacht without diversion of his forces to unprofitable waters. Just the preceding month he had written in his war diary: “The tonnage battle is the main task of the U-boats…. It must be carried on where the greatest successes can be achieved with the smallest losses.”

But the new appointment also had its disadvantages, principally, as Raeder, who nominated him for the post predicted, that as C-in-C Dönitz “would not be able to dedicate himself to the immediate conduct of the U-boat war to the same extent as formerly.” The “Lion,” as U-boat men admiringly called him, had already suffered physical distancing from his underseas fleet and their crews, when in March 1942 a British raiding party attacked St.-Nazaire; alerted to how easily such a raid might be made on BdU itself, Dönitz reluctantly abandoned Kernével and established his headquarters in an apartment complex on the Avenue du Maréchal Maunoury in Paris. Now, to consolidate BdU with his new post as C-in-C, he moved U-boat headquarters even farther east, to the Hotel am Steinplatz in the Charlottenburg suburb of Berlin (losing two railroad cars filled with equipment and papers in the process), where BdU became operational on 31 March 1943. It had been Dönitz’s presence on the dock at Lorient and the other bases, where he attended to his crews’ leavings and returnings, that cemented his standing as a father figure to his men and elicited a depth of loyalty from ranks and ratings that was unprecedented in the Kriegsmarine. Now his inspiring figure and voice were far from the bases, with what negative impact it is impossible to calculate.

With his longtime Chief of Operations Branch (BdU-Ops), Konteradmiral Eberhard Godt, Dönitz incorporated BdU into the Naval Staff as its Second Section, with Godt, Chief of Staff, overseeing day-to-day conduct of U-boat operations—although in the war diary, where major convoy battles are described and where strategies or policies are declared, one continues to hear the voice of Dönitz, with the result that in the chapters that follow in this narrative the citations of passages from the diary assume their authorship by a Dönitz/Godt duumvirate. The entire BdU operations staff numbered barely more than a dozen officers, most of them in their early thirties (Dönitz was 51, Godt 42). Though it could draw upon the much larger Naval Staff for such things as Intelligence (3/Skl), Communications Service (4/Skl), Radar Countermeasures (5/Skl), and Meteorology (6/Skl), it remained a thin blue line for trying conclusions with the combined staffs of the Admiralty and Coastal Command, not to mention GC&CS. (Western Approaches alone had a staff of over a thousand officers and ratings.)

The third major change in command came in RAF Coastal Command, where Joubert was succeeded as AOC-in-C by Air Marshal Sir John Slessor on 5 February 1943. A Royal Flying Corps pilot in the Kaiser’s war, Slessor had fought off Zeppelins over London and flown artillery observation missions over the trenches of France. His most recent posts in the Führer’s war were Commander of 5 Group of Bomber Command and Assistant Chief of the Air Staff (Policy). With Air Chief Marshal Sir Charles F. A. Portal, Chief of the Air Staff, he attended the Casablanca Conference, actually held in a residential suburb of the city called Anfa, where, from 14 to 23 January, Churchill, Roosevelt, and their Combined Chiefs of Staff conferred on the priorities to be established for future operations. He was present when the conferees approved their final Memorandum, “Conduct of the War in 1943,” with, at its head, the now well-known “First Charge” declaration: “The Defeat of the U-boat must remain a first charge on the resources of the United Nations.”

Slessor wrote after the war that the person responsible for having that strategic imperative given first ranking was Admiral Ernest J. King, though King’s biographer does not mention it, except to say that, “Everyone agreed that the Battle of the Atlantic took first priority.” Slessor did not think that the “First Charge” declaration had much practical influence on the anti-U-boat war, except to prod the Air Ministry to divert some of the newly available centimetric radar sets from Bomber to Coastal Command. It was not until March, however, that the first Coastal squadron equipped with 10-centimeter ASV Mark III became operational. That squadron, which flew L/L Wellingtons, was then in a position to defeat the Metox receiver, and so surprise the surfaced U-boats at night as L/L aircraft had done up to six months before. The pure hunt was on again. Or was it?

The Admiralty pressed Slessor to make immediate and maximum use of the centimetric aircraft in the Bay of Biscay, and to take full advantage of the interval of time before the Germans developed a new search receiver to detect 10-centimeter pulses. But Slessor balked at going back to the Bay Offensive, as he stated in a Note to the Prime Minister’s Anti-U-Boat Warfare Committee, of which he was a member. The A.U. Committee, as it came to be called, had been formed subordinate to the War Cabinet on 13 November and thereafter met weekly at No. 10 Downing Street under the Chairmanship of the Prime Minister. Its membership was composed of (with varying attendance and occasional visitors) twenty-two Ministers, Admirals, and Air Marshals, together with the scientists Blackett, Watson Watt, and Lindemann (now Lord Cherwell), and Mr. Averell Harriman, President Roosevelt’s personal envoy to the United Kingdom.

To this top-level body, on 22 March, Slessor sent his five-page Note accompanied by a twenty-five-page statistical analysis of the Bay Offensive from June 1942 to February 1943 and of the air cover given threatened convoys from September 1942 to February 1943. The analysis had been done by Coastal’s O.R.S., then headed by Professor Waddington, which Slessor valued and supported no less than Joubert. The analysis showed, wrote Slessor, that whereas on the Bay patrols there had been one sighting of a U-boat for every 164 hours flown in the period June to September, and one sighting per 312 hours from October to February, there had been one sighting per only 29 hours flown over threatened convoys. While the Bay patrols of No. 19 Group (Air Vice Marshall Geoffrey Bromet) had resulted in a certain number of kills, the lethal rate was a low 7 percent of attacks made, hardly justifying the disproportionate and uneconomical effort employed. Slessor therefore proposed reducing the scale of the Bay Offensive. “Our policy,” he concluded, “should be to concentrate the greatest practicable proportion of our available resources on close cover of threatened convoys, the Bay patrols assuming the position of a residuary legatee.”

When on 24 March this recommendation was placed on the table by the A.U. Committee for discussion one week hence, the Admiralty found themselves rebuked in their desire to pass from the defensive to the offensive in the U-boat war by going full-bore in the Bay. This was all the more vexing since Slessor’s Command was technically under the operational control of the Admiralty. One week later, however, as shown in chapter 8, Their Lordships would be back with a counter-strike—and the Americans alongside them.

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Professor Blackett left the O.R.S. of Coastal in January 1942 to become Chief Advisor on Operational Research (C.A.O.R.) to the Admiralty. In that capacity he recruited a prestigious scientific team similar to that at Coastal—Evan Williams would follow him to Whitehall in January 1943—and cast his practical intellect across the whole range of naval operations, including, in a notable study, the optimum size of convoys. For years the number of ships in convoy had hovered at around forty-five, though the origin and rationale for that rule could not be found by Blackett. A formation larger than that was assumed to be dangerous, since it presented so many targets.

When in late autumn 1942 Blackett investigated convoy statistics for the two-year period 1941–1942, he was startled to find that convoys averaging thirty-two ships had 2.5 percent losses, but that convoys averaging fifty-four ships suffered only 1.1 percent losses. Those figures offended common sense, and Blackett knew that his team would have to develop convincing reasons to explain them. One reason was readily apparent: while the fifty-four-ship convoy occupied a larger sea area than a thirty-two-ship convoy, the guarded perimeter of the area did not expand by the same proportion. And several weeks of hard analysis produced these findings:

It was found: (a) that the chance of a convoy being sighted was nearly the same for large and small convoys; (b) that the chance that a U-boat would penetrate the [escort] screen depended only on the linear density of escorts, that is, on the number of escort vessels for each mile of perimeter to be defended; and (c) that when a U-boat did penetrate the screen, the number of merchant ships sunk was the same for both large and small convoys—simply because there were always more than enough targets. These facts taken together indicated that one would expect the same absolute number of ships to be sunk whatever the size of convoy, given the same linear escort strength, and thus the percentage of ships sunk to be inversely proportional to the size of the convoys. Hence the objective should be to reduce the number of convoys sighted by reducing the number of convoys run, the size of the convoys being increased so as to sail the same total number of ships.

Even with these data in hand, Blackett had difficulty convincing the Naval Staff to enlarge the size of convoys, since the staff worried about the vulnerability of a sixty-ship convoy to frontal attacks, an increasingly popular U-boat tactic, as well as about communication and control problems. He eventually won them over, however, and the Admiralty, in turn, at the 3 March meeting of the A.U. Committee, gained that body’s approval to start running sixty-or-more-ship convoys on a case-by-case basis, as would be done. A sixty-one-ship convoy, HX.231, departed Halifax on 29 March escorted by one frigate (SO), one destroyer, and four corvettes (Escort Group B7; see chapter 4). Helped by a Support Group and Liberators bombers air cover, it arrived at Londonderry 95 percent intact. Blackett wrote later that it was unfortunate he had not appreciated the importance of the convoy size question much earlier than he did. During the preceding year alone 200 ships might have been saved.

In a report to the A.U. Committee dated 5 February, Blackett threw himself into the defense versus offense debate that was then brewing in all the pertinent Commands. Without taking sides, he presented the “defensive values” of saving ships and the “offensive values” of attacking U-boats. Briefly stated, the defensive value of the surface escorts was found, first, by noting that shipping losses in the North Atlantic during the last six months of 1942 were at a rate of 210 ships per year, while the average number of escorts was 100. Since the statistics showed that the number of ships torpedoed per submarine present in an attack decreased as the escort force increased, and that an increase of the average escort strength from six to nine would be expected to decrease the losses by about 25 percent, had there been an additional 50 escorts available in the time period cited losses should have been reduced by fifty-ships (25 percent). Or, expressed differently, each escort vessel would have saved about one ship a year.

In determining the offensive value of surface escorts, the assumption was made that the sinking of a U-boat saved the shipping it would have sunk in subsequent months. If the escorts sank seven and damaged eight U-boats, and the eight damaged could be considered the equivalent of two additional boats sunk, since the statistics showed that about 0.4 ships were sunk per month by each operational boat, an average of 3.6 ships were saved by the sinking of a U-boat. In their offensive role the 100 escorts saved about 0.7 ships per escort vessel per year. A comparison of the defensive and offensive numbers gave the edge to the defense. Where aircraft were concerned, Blackett made similar assumptions and calculations. Using air cover over threatened convoys in the period cited, for defensive value, he calculated that each long-range aircraft in its average life of forty sorties saved about thirteen ships by defensive action. By contrast, where aircraft conducted hunting operations independent of convoys, for example, the Bay Offensive and other search and attack sweeps, the offensive value obtained from the maximum number of sorties flown by one aircraft was about three ships saved. Again, the results favored the defense.

All through March and April the defense-offense question was debated at Western Approaches, where there was increasing criticism that the current policy—“The safe and timely arrival of the convoy at its destination is the primary object of the escort”—was insufficiently bold. Even the role of the Support Groups as ancillary to the close escorts was thought by some to be a waste of their aggressive potential. Admiral Horton, whom no one could accuse of lacking in offensive spirit, and who longed for the day when he could simply “attack and kill,” nonetheless approached the question carefully, mulling over what was known of recent enemy contact and behavior.

During April sixteen convoys were attacked and suffered loss, in no case severe, however; the largest number of ships torpedoed in any one convoy was four. Of those, seven were transatlantic convoys (HX.231–234 inclusive, ON.176 and 178, and ONS.3). The typical U-boat Commander still preferred to attack on the surface at night despite the fact that radar and snowflakes (illuminants) had made that a more hazardous action than it was the year before. The U-boats now strove to get ahead of a convoy, apparently so that they could attack submerged if success on the surface seemed unlikely. In making follow-up attacks, U-boats took advantage of the disturbance created by first attacks, and they displayed a tendency to follow one another in from the same direction, from a mile or two back. Boats detected and driven off by the escorts at night frequently made no additional attempts to attack during the remainder of the night; thus, the boats had only to be detected for the battle to be half-won.

With present enemy policy, most attacks developed in front of the beam of the convoy. The U-boats were attacking more eastbound than westbound convoys, no doubt because the latter carried no cargo and were under first-class air protection for the first 600 miles of their run. Their tendency was to operate primarily in the area between 500 and 700 miles to the northeast of Newfoundland, presumably to be outside the range of aircraft based in Iceland and Ireland, air cover from Newfoundland not apparently being much of a concern to them.

Horton then considered various aspects of escort work: Practically every U-boat sunk during the past year was destroyed prior to its attack on a convoy, not afterward. U-boats were most effectively dealt with when they were on the surface, now that asdic was no longer the escort’s only weapon; therefore, forcing a U-boat to dive was not always the best policy. Analysis of asdic figures on lost contact for the last six months of 1942 showed that sixty-four percent of boats were at depths of less than 200 feet when lost. And since the morale of the Merchant Navy was showing signs of strain, it was undesirable to use convoy ships as “bait,” that is, to accept the sinking of merchant ships as a way of indicating the presence of a U-boat so that it might be attacked.

With that, however, Horton in effect threw up his hands. None of the recent data were any help in resolving the defense-offense question. To defend or to hunt? He finally decided that the Tactical Policy “must still be the safe and timely arrival of the convoy.” But there was no reason he could not have it both ways. He left the Escort Groups open to “exercise their initiative under all circumstances,” thus giving them authorization to take such offensive action as seemed prudent, necessary, and opportune, while making certain that the convoys under their care were not unduly exposed to enemy attack. “The matter was largely a question of numbers,” he wrote in a signal sent on 27 April to all British and Canadian Escort and Support Groups under CinCWA. “Whatever form of warfare is considered, the question of the strength of the opposing forces must play a very large part in deciding whether an offensive or defensive role can be adopted.” The defense-offense question, then, would not be decided at Derby House. It would be decided at sea.

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  1. TO DEFEND

The Battle for ONS.5

The safe and timely arrival of the convoy at its destination is the primary object of the escort. Evasion attains the primary object, and should therefore be the first course of action considered. At the same time, it must be borne in mind that if enemy forces are reported or encountered, the escort shares with all other fighting units the duty of destroying enemy ships, provided this duty can be undertaken without undue prejudice to the safety of the convoy. ATLANTIC CONVOY INSTRUCTIONS

FORTY-THREE MERCHANT SHIPS that would make up Outward North Atlantic Slow Convoy Five, abbreviated ONS.5 and code-named MARFLEET, assembled for their voyage on 21–22 April. Destination: Halifax, Nova Scotia, with detachments to Boston and New York. Mostly gray in color, their names painted out, they had sailed from five different ports—Milford Haven, Liverpool, the Clyde, Oban, and Londonderry—and now had rendezvoused off a lighthouse-crested rock called Oversay that rises from the sea at the North Channel entrance between northeast Ireland, the southern isle of the Inner Hebrides, and the Mull of Kintyre. There, over a twenty-four-hour period, the convoy Commodore J. Kenneth Brook, R.N.R., formed his charges, three and four deep, into a broad front of twelve columns. At the center, in column six, Brook stationed himself ahead in the Norwegian ship Rena, with only the New York-bound American oiler Argon astern.

Most of the ships were elderly tramp steamers. Most were British, but McKeesport, West Madaket, and West Maximus, as well as Argon, were of United States registry; Bonde, Rena, and Fana were Norwegian; Berkel and Bengkalis were Dutch; Agios Georgios and Nicolas were Greek; Ivan Topic Yugoslav; Isabel Panamanian; and Bornholm Danish. Two ships, McKeesport and Dolius (British), had been with SC.122 when that convoy was savaged by U-boats on 17–20 March. There was not a ship at R/V Oversay that had not sailed in convoy before. The majority were steaming in ballast, bound eventually for North and South American ports where they would load up food, fuel, raw materials, and finished weapons. Seven ships carried coal (“coal out, grain home”), four had general cargoes, and one listed general cargo and clay. Three ships in addition to those at Oversay were to join the formation at sea from Reykjavik, Iceland, on 26 April: Gudvor, Bosworth, and the U.S. Navy tanker U.S.S. Sapelo, which was returning to the States in ballast. Most of the convoy vessels were Defensively Equipped Merchant Ships (D.E.M.S.) with single four-inch guns manned by Navy and Army gunners. Gross Register Tonnage varied greatly, from tiny Bonde at 1,570 tons to the largest freighters at plus or minus 10,000 GRT.

Whatever their size, the merchantmen were expected, once underway, to maintain a speed of seven and a half knots, though their Masters knew, with gale-force seas forecast along the westward course, that was not a likely prospect. The ships’ crews also varied in composition, most of them British Merchant Navy, some U.S. Navy and Merchant Marine, others East Indian or Asian in whole or in part except for officers. Most crew had small canvas “panic bags” for carrying their most valued possessions into the lifeboats, if that became necessary; the Americans’ bags were more the size of railroad luggage.

By 1200 on 22 April this unexceptional, businesslike merchant fleet was formed up at Oversay with 1,000 yards separating the columns and 800 yards between each ship ahead and astern. The entire formation occupied eight and three-quarter square nautical miles. The shepherd, Commodore Brook, had gathered his flock. Now he awaited the sheepdog, who, he hoped, would hold the sea wolves at bay. At 1400 the sheepdog arrived in the person of Commander Peter Gretton, R.N., Senior Officer Escort, aboard the destroyer HMS Duncan, accompanied by the frigate HMS Tay, the corvettes HMS Loosestrife, HMS Pink, HMS Snowflake, and HMS Sunflower; two rescue trawlers, Northern Gem and Northern Spray, and the tanker British Lady.

Together, the warships made up Escort Group B7, the midocean close escort screen charged with seeing convoy ONS.5 to a “safe and timely arrival” at its assigned destination on the opposite shore.’ A second destroyer, H.M.S. Vidette, had been sent ahead to escort the two freighters and the USN tanker from Iceland to a midocean rendezvous with the main body. HMS Vidette’s Captain, Lieutenant Raymond S. Hart, R.N., was the only regular officer besides Gretton in the group. Two corvette Captains were Australians, one was Canadian; several officers were New Zealanders.

Thirty-year-old Peter William Gretton was educated at the Dartmouth and Greenwich Royal Navy colleges, and, rather than select a career specialization, which was the usual route to promotion, he chose to remain a general seaman officer, or “salt horse.” In a nod to specialization he learned to fly and amassed fifty hours of solo time, though he pronounced himself “not a good pilot.” In 1936 he earned a Distinguished Service Cross (DSC) leading a landing party at Haifa during the Arab rebellion in Palestine. Three years later, as war with Germany loomed, he did a week’s course in anti-submarine warfare at Portland, HMS Osprey. That experience, together with his flying, would give him a leg up in understanding the U-boat war when it came. His hankering had always been for destroyers, and he counted himself lucky to be appointed First Lieutenant of the famous destroyer HMS Cossack, on which he served in the Second Battle of Narvik, where he was mentioned in dispatches. In 1941 he received his own destroyer command on HMS Sabre, and entered convoy escort duty full-time. Transferred to command of the destroyer HMS Wolverine in 1942, he helped escort the celebrated Malta convoy(Conhvoy Pedestal which I wrote in detail in anotther thread) in August of that year and, while steaming in the Mediterranean at 26 knots, rammed and sank the Italian submarine Dagabur, with the loss of all hands, for which action he was awarded the first of three Distinguished Service Orders (DSOs).

During the weeks when the crumpled bows of HMS Wolverine underwent repair, Gretton took the anti-submarine warfare course devised by Captain Roberts at the Tactical Unit in Derby House, Liverpool. The schooling was a turning point for Gretton in several ways. First, he learned how unaware he had been of German submarine tactics and of the best means for frustrating them by use of the latest shipborne detection and weapons technology. Under Roberts’s tutelage, he quickly filled in the knowledge gaps.

Above all, Roberts stressed, effective ASW seamanship meant learning how, perhaps for the first time, to think. War at sea had changed. Courage and endurance were no longer enough. Victory over the U-boat required the intelligent use of technical aids, particularly HF/DF, 10-centimeter radar, and asdic, in that sequence. Second, Gretton realized at Derby House how much convoy duty had been denigrated by the regular Navy, which esteemed big ship-big gun fleet actions and considered the passive tending of seaborne trade as beneath their dignity, with the result that all the best officers went to the Home and Mediterranean fleets, while the failed careers and incompetents ended up in Western Approaches—with certain very notable exceptions, for example, Captain Frederic John Walker, R.N., and Captain Donald Macintyre, R.N., salt horses like Gretton. There was a desperate need in the Atlantic of more good regulars, he concluded (and when, belatedly, in 1943–44, the Home Fleet regulars realized that the Atlantic was where the war was, they climbed over each other to get Escort Group commands). Third, Gretton determined that if ever he received an Escort Group command of his own, he would bring his regular and reserve officers up to Roberts’s—and now his—exacting high standards.

Commodore Peter Gretton

Commander Peter Gretton , CO of Escort Group B7 that led critical passage of Convoy ONS.5

That brass hat came in December 1942 when he was advanced to command of Escort Group B7, based at Londonderry. There he embarked in the new twin-screw River class frigate HMS Tay, while the destroyer assigned to him, the eleven year-old, 329-foot, D-class flotilla leader HMS Duncan, was refitting in Tilbury docks prior to recom-missioning. The B7 Group had just come off a rough convoy engagement in which the Senior Officer Escort (SO) and his ship had been lost, but Gretton found his ships to be “in great heart.” Throughout January, February, and March, a period of expanding U-boat activity, he led them on cross-Atlantic passages that were, ironically, eventful for their lack of U-boat contacts. “For three months the group ran hard but had nothing to show for it but rust,” he wrote later. “We seemed always to steer clear of the wolf packs, which were then at the height of their success.”

Aboard HMS Tay he had his first sea experience with an HF/DF set. The Type FH3 equipment could identify the general position of a U-boat transmitting to base or to another boat on a high-frequency wave band, even indicate whether the U-boat was near or far. More exact “fixing” of a U-boat’s position required the “cross-cut bearing” provided by a second HF/DF-equipped ship, as Duncan would be when recommissioned. Between sailings Gretton worked his officers and technical ratings hard at Londonderry’s asdic and depth charge trainers, radar and HF-DF detection simulators, and the new Night Escort Attack Teacher, where all ranks and ratings who manned detection and communications equipment, the plotting table, or the bridge received intensive and realistic attack drills in nighttime conditions. Time and again they practiced on land the tactical maneuvers they would have to carry out at sea, which bore such code names as Raspberry, Half-Raspberry, Observant, and Artichoke.

Gretton was relentless in the conduct of these exercises and he was quite prepared to sack anyone who flagged in the effort. Among his Captains he had the reputation of an egotist but a gentleman, a hard man but a fair man. “Kindness to incompetents seldom provided a dividend,” he wrote after the war “whereas severity invariably paid. As [German Field Marshal Erwin] Rommel said, ‘The best form of welfare is hard training.’ … But the sailor will never admit it.” Gretton had no need as yet to purge this group, however, and the men of B7 seemed to have welded into a tautly skilled team.

Group B7 finally got its blooding in early April when it relieved a Canadian group escorting the fast (nine knots) Convoy HX.231 from New York to the United Kingdom. Entering the mid-Atlantic Air Gap on 4 April, B7 soon had more than enough U-boat contact to make up for its sterile months, as for over four days and nights it battled a pack of fourteen boats. HMS Tay, commanded by Lieutenant-Commander Robert Evan Sherwood, R.N.R., made asdic contact with one of them, U-635, and sank her with a well-placed pattern of depth charges. Another boat, U-632, had been sunk earlier by a RAF Coastal Command Liberator aircraft from Iceland. And U-294, badly damaged by depth charges, was forced to return to base. But six merchantmen were lost in the exchange: three in convoy and three stragglers.

The first loss, that of the British motorship Shillong, was the worst for Gretton. Loaded with zinc concentrate and wheat in bulk, the 5,529-GRT vessel sank from view within two minutes of being torpedoed, casting her entire crew into the sea. On her search for the U-boat, HMS Tay passed slowly through the bobbing survivors, their life jackets aglow with red lights. Gretton shouted encouragement to them, but knew that pursuing the U-boat was his most urgent duty, lest others be attacked, and that Tay must not lie hove to lest a torpedo remove her from the screen. But, as late as 1964, when he wrote about the men he left to die, he called the moment “my most painful memory of the war…. ”

Finally, a mist descended on the ocean swells and ruined the visibility of the U-boats. On 7 April aircraft roared overhead in great numbers. Eventually, landfall was made off the north coast of Ireland, and B7 reentered its home port at Londonderry. Ninety-five percent of the convoy had come through the pack battle unharmed, and B7 had acquitted itself well in its first real trial of pluck and mind. Gretton was pleased—except with the performance of Loosestrife, whose Captain, in his view, had not shaped up to standards, and whom he promptly replaced.

Waiting for Gretton was the recommissioned HMS Duncan, which not only gave him a destroyer to go with the frigate HMS Tay, but also gave him a second HF/DF set (Type FH4), which made possible cross-cut bearings in combination with HMS Tay’s FH3, which alone during HX.231 had proved “worth its weight in gold.” HMS Duncan was also reequipped with the latest asdics, Type 271 10-centimeter radar, and radio transmitters and receivers. On deck she mounted two guns, two torpedoes, and the new forward-firing impact-fused “Hedgehog.” Extra depth charge stowage had been created. His complement of 175 officers and men was unknown and untried, however, and he immediately set them to work jousting with last war-type submarines in the Londonderry exercise area, except on those days when he was asked to review HX.231 with Admiral Horton (CinCWA) in Liverpool, address a large audience of officers on the same operation, and huddle with RAF Coastal Command pilots on how better surface and air escort cooperation might be promoted.

Then came the date, long predetermined, for ONS.5.

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As he pulled alongside the Commodore’s ship, Rena, Gretton exchanged documents with Brook, whose orders had come from the Trade Division of the Admiralty, and advised him by loud-hailer of the disposition of his forces. Gretton stationed Duncan in the center behind Argon and formed up the rest of his force on the port bow, beam, and quarter, and on the starboard bow and quarter, with the tanker and rescue trawlers astern. The screen in place, Brook signaled his convoy to gather way on course 280°. Notwithstanding the confidence B7 had gained from HX.231, Gretton had every reason at this moment to be apprehensive. He was sailing northwestward into what forecasters told him was atrocious weather with gale-force winds. That meant that his convoy ships, light on the water because they were in ballast, would be buffeted about like so many champagne corks, and that would work havoc with stationkeeping, throw some ships out of control, and leave others stragglers. Maintaining seven and a half knots would be impossible under those conditions. Furthermore, their course, northwest to 61°45’N, 29°II‘W, a position east of Ivigtut on Greenland, and thence southwest along the Great Banks of Newfoundland, would engage his fleet with pack ice and bergs.

Gretton knew that Western Approaches thought that the northern route was worth the hazard, since aircraft could provide cover south and to the west. Even so, while bombers could fly along much of his route from bases in Northern Ireland and Iceland, ONS.5 eventually would enter the Air Gap longitudes below Greenland that most of those aircraft could not reach. And that was where he assumed the majority of U-boats would be lurking. Were they perhaps already stationed directly athwart his course? Western Approaches had assured him that it had routed ONS.5 through waters that were least expected to be U-boat-infested. It may have informed him, furthermore—the surviving records do not say—that Admiral Donitz had a record number of boats at sea (27 on return passage) and that probably as many as 36 boats were formed into two operational patrol lines, Meise and Specht (Woodpecker), positioned along an arc 500 miles east of Newfoundland.

It could not give him the source of these data because Gretton, like other commanders of his duty and rank, was not “indoctrinated,” that is, in the know about “Z,” or “Special Intelligence,” which was distributed through one-time pad ciphers to a tightly restricted list of recipients in the source-disguising form called “Ultra.” Nor could Western Approaches inform him that the German communications monitoring and cryptographic service, B-Dienst, had possibly discerned ONS.5’s course from decrypts of the Anglo-American Naval Cipher No. 3 (“Convoy Code”). If that was so, it is not known on exactly what day such information might have been communicated to BdU. B-Service messages to BdU no longer exist. Weekly summaries of B-Service information do exist, in the Bundesarchiv-Militararchiv in Freiburg im Breisgau, but the summary for the week of 19–25 April contains no mention of ONS.5. Decryptions of the convoy code were not always current.

An example of the time lag between interception and decryption is the mention of ONS.5 that occurs in the Weekly Summary of 10–16 May, which begins: “The Iceland detachment of ONS.5 consisting of at least three merchant ships [escorted by H.M.S. Vidette] was to leave port at 0715 hours on 23 April in order to rendezvous with the main body [of the convoy] during the daytime of 26 April…. ” Obviously, with such a delay this information had no operational value. The first mention of ONS.5 in the weekly summaries dates from 26 April-2 May, and relates to Third Escort Group (EG3), which will be considered below.

The first week of the voyage went about as Gretton expected. There was the usual mechanical mishap. At 2200 on the first night, the Polish Modlin (3,569 GRT), beset by engine trouble, parted company with the eighth column and returned to the Clyde. At daybreak on the 23rd the weather worsened. High waves and strong winds forced numerous ships out of position. B7 busied itself chivvying stragglers back into line all that day and night. As much as he could, HMS Duncan kept to the center column, No. 6, and maintained the convoy’s slow speed as a means of saving fuel, since the refitted destroyer had been improved in every way except in fuel consumption, for which she was notorious. Her daily consumption at slowest possible speed was 8 percent. At 1630 on the 24th, despite continued heavy seas, HMS Duncan closed with British Lady in an attempt to top up his bunkers, but after the tanker discharged only two of her 600 tons the buoyant wire and rubber hose streamed astern parted, and HMS Duncan had to withdraw and wait for calmer seas. Refueling from Argon was impossible, he discovered, except in mirror-flat water, since the positioning of the American oiler’s canvas hoses would require HMS Duncan to come alongside—too dangerous a maneuver in high seas. The uselessness of Argons precious cargo was foreboding.

HMS Duncan and HMS Tay made regular HF/DF sweeps for U-boats transmitting to BdU or to other boats, but heard nothing. Actually, there was a U-boat not far ahead on their course, but for some reason, still unclear, it had not made a transmission to BdU since sortieing from Kiel, Germany, on 15 April. B7 would not learn of its presence until later in the evening of the 24th, when the boat was attacked by Boeing Flying Fortress “D” of No. 206 Squadron based at Benbecula in the Outer Hebrides. RAF Flying Officer Robert Leonard Cowey was piloting eight miles northwest of ONS.5 on a plan devised by Coastal Command to give the convoy cover from the afternoon of the 24th to midnight on the 27th.

At 1725 one of his crew sighted a fully surfaced U-boat ten miles distant. It was U-710, a newly commissioned Type VIIC, on her first war cruise, under an untried commander, Oblt.z.S. Dietrich von Carlowitz, who was probably unaware of the convoy’s proximity. Instead of alarm-diving at the appearance of Cowey’s aircraft, which was normal U-boat behavior, Carlowitz sent a crew to man the anti-aircraft guns on the platform aft the tower. Inaccurate tracers brushed by as Cowey dove the four-engine bomber to the deck and released a stick of six depth charges (D/Cs) that straddled the U-boat at right angles to her track. The brand-new bows heaved vertically from the explosions and the rear gunner watched the hull of U-Boat sink stern-down in a froth of debris. Cowey circled back and dropped another stick into the wreckage, after which he counted twenty-five survivors flailing in the water. There was nothing anyone could do for them. Low on fuel, and his home base closed in by weather, Cowey headed for Reykjavik. Allies drew first blood from Germans in battle of ONS 5.

For ONS.5, dawn broke on the 25th with the ocean surface in a state of upheaval. Commander Brook struggled to keep his ships in station as howling winds and fierce wave action forced numerous vessels out of line. Brook recorded: “Convoy making 2–3 knots, steering badly.” These conditions continued into the night when, at one point, Brook and Gretton could see seven different sets of “two red lights vertical” from ships that were Not Under Control. The inevitable happened, as HMS Duncan signaled Western Approaches: DURING GALE LAST NIGHT NO. 93 BORNHOLM COLLIDED WITH NO. 104 BERKEL. BOTH DAMAGED 104 IS CONTINUING BUT BORNHOLM LEFT UNESCORTED FOR REYKJAVIK AT 1400. The collision occurred at 2355 when the convoy was proceeding at no more than 2 knots on course 301°. Brook, who did not learn of the accident until the next morning, reported that Bornholm was holed in the Engine Room about 10 feet above the waterline. He commented that progress made against the stormy seas that night was so slight that the convoy was “to all intents and purposes hove-to.”

A moderate gale continued through the morning hours of the 26th, when all ships were sighted but scattered. B7 managed to whip in all but No. 81, Penhale, lead ship of column 8, which straggled astern so badly Gretton detached her to Reykjavik, escorted by Northern Spray. During the forenoon hours convoy speed was 3 knots. At 1400 Gretton was cheered by the arrival of the Iceland contingent—B/s second destroyer, HMS Vidette, with the British Bosworth, the Norwegian Gudvor, and the empty U.S. naval tanker Sapelo—which had been homed to ONS.5’s position by HF/DF and an RAF PBY Catalina. HMS Vidette gave Gretton a destroyer not only faster (25 knots) than HMS Duncan but the twenty-five-year-old V&;W (Long-Range Escorts) Class vessel also had “longer legs,” owing to the removal of one of her boilers and the installation in the vacated space of extra oil stowage. HMS Vidette was equipped with asdic and Type 271 radar, though not with HF/DF; hence she could not join HMS Duncan and HMS Tay in acquiring cross-bearings on U-boat transmissions. Gretton continued to fret about HMS Duncans ability to continue at sea. Unless the weather cleared, he signaled Western Approaches, he might have to separate and refuel in Greenland.

Fortunately, the seas subsided the following morning, long enough for HMS Duncan to top up successfully from British Lady, completing the process at 1100. He was followed by HMS Vidette and the corvette HMS Loosestrife, while RAF Hudsons from Iceland provided cover overhead. Later that day Northern Spray rejoined the convoy. Gretton recorded his position as 61°25’N, 23°49’W, south of Reykjavik and due east of Cape Discord on Greenland. So far there had been no sightings or electronic detections of U-boats. Except for the boat sunk three days before by Fortress “D,” there seemed to be no boats around. If there were, perhaps they were concentrated on a mid-Atlantic convoy known to be on the reciprocal of the same northern course that swept the southern tip of Greenland: The heavily laden SC.128, which departed Halifax on 25 April for the United Kingdom, had been routed to pass north and west of the U-boat groups known to the OIC Tracking Room as of its sailing date.

Between the 22nd and the 25th the Specht and Meise groups, together with new U-boats just arrived in the area, had been reshaped by BdU to form three Groups: Specht, Meise, and Amsel (Blackbird). The Specht line, with seventeen U-boats, ran from 54°15’N, 43°15’W to 51°15’N, 38°55’W. An augmented Meise line, with thirty boats, ran from 59°15’N, 32°36’W to 56°45’N, 28°12’W. The Amsel line, with eleven boats, ran from 54°51’N, 32°00’W to 53°45’N, 29°35’W.12 The BdU orders establishing these dispositions originated as part of a plan to catch westbound ONS.4, but that convoy arrived at New York safely and intact. Two other convoys on northern courses, SC.127 (departed Halifax 16 April) and ON.179 (departed Liverpool 18 April) successfully eluded the patrol lines, SC.127 being diverted to a more northerly course on the 26th after the order enlarging Meise was decrypted nearly fourteen hours after its interception13—and just under the wire, as will be shown below. Convoy ON.180 (departed Liverpool 24 April), which trailed ONS.5, similarly would evade the patrol lines. With the majority of U-boats in northern latitudes, two other U.K.-bound convoys that were at sea in this period, HX.235 and HX.236, were safely directed along southerly courses.

Two entries in the BdU war diary for this period are significant for revealing German operational failures and intelligence misjudgments. The first entry, dated 25 April: An earlier eastbound convoy, HX.234, which sailed the northern route and made port in the U.K. with two ships sunk and one damaged, had been pursued for four days (21–25 April) by no fewer than nineteen boats. The investment of that much energy and time had yielded disproportionately small success. In explaining the failure, Admiral Donitz and Chief of Staff Godt enumerated unfavorable weather, particularly snow and fog; changing visibility conditions; the shortness of the nights on the northern route; strong air cover from Greenland and Iceland; and (cited twice) “the inexperience of the large number of new Commanders who were not equal to the situation.”

The second entry, dated 27 April: the BdU reflected on the fact that on the day before, convoy SC.127 had suddenly changed to a more northerly heading and had passed untouched through a temporary seam between Groups Meise and Specht, which at the moment were maneuvering to new positions. Furthermore, an intercepted American U-boat Situation Report revealed that the Allies knew exactly where the U-boat groups were deployed as well as their current movements, and had the capability to reroute convoys accordingly. How had the enemy gained such knowledge? The BdU answered: “This confirms, more than ever, the suspicion that the enemy has at his disposal a radar device especially effective in aircraft, which our boats are powerless to intercept.”

Of course, it is true that the Allies had 10-centimeter airborne radar, undetectable by any equipment with which the U-boats were then supplied, but its average range sweep was fifteen miles, hardly what would be required to descry the positions of even one wolfpack. Apparently Dönitz and Godt more readily believed in the existence of a (for then) preternatural eye in the sky that laid bare anything that moved across thousands of square miles of ocean than that Allied cryptographers had simply done what B-Dienst had done: cracked the other side’s cipher. That commonsense conclusion—a kind of Ockham’s Razor—never swayed BdU’s mind, and Dönitz himself obstinately refused to entertain the likelihood throughout the war and after it. (He similarly refused to believe at this time, as earlier noted, that the Allies possessed shipborne HF/DF capability.) But had he been aware that cryptographic intelligence was the source of the Allies’ uncanny knowledge, Dönitz would have been greatly encouraged by something else that happened on the day that SC.127 slipped past harm’s way: the Allied cryptographers went blind.

At 1200 on 26 April, owing to changes unexpectedly introduced by Berlin in naval Enigma settings, GC&CS and the OIC Submarine Tracking Room abruptly ceased reading U-boat traffic, and would not read it again until the afternoon of 5 May, a critical period in ONS.5’s westward voyage, since it was during those nine days of cryptographic intelligence blackout that Commander Gretton’s convoy would enter the longitudes where U-boat packs were known to be maneuvering in strength. With what Rodger Winn called “no precise information,” the most that he and Patrick Beesly in the Submarine Tracking Room could tell CinCWA Admiral Horton after 26 April was that three U-boat groups were still thought to be “in the general area off Newfoundland.” As Winn wrote later, “Thus [where ONS.5 was concerned] it was not possible to attempt any evasive routing although the convoy had in the first place been routed as far north as possible to avoid U-boats.’ Three westbound convoys earlier in April, ON.178, ONS.3, and ONS.4, also had been routed north by the tip of Greenland, with small losses to the first two and none to the third. Perhaps ONS.5 would be as lucky.

The OIC Tracking Room was not without alternative sources of information, as noted earlier. Wireless transmissions from the U-boats could be DFed by a shore-based HF/DF network that supplied cross-bearings in the Atlantic theater; the U.K. had twenty stations, the U.S. sixteen, and Canada eleven.19 Furthermore, short signals (Kurzsignale) in the old, still readable Hydra cipher (as Heimische Gewässer had been renamed on 1 January 1943) transmitted by Räumboote (motor minesweepers) escorting U-boats in and out of their Baltic and Biscay bases enabled Winn and Beesly to calculate daily the number of boats at sea; and they took into account the fact that by 26 April BdU had three Type XIV tanker and supply boats—Milchkühe—U-487, U-458, and U—461, on station in mid-Atlantic, which could extend the time some of the attack boats, after refueling, could remain on operations. No alternative source, however, could give Winn and Beesly the same confidence that their Main North Atlantic Plotting Table represented actual conditions at sea as that provided, when readable, by crisply accurate “Z,” particularly at those times when U-boat groups were regularly forming, re-forming, or shifting their operational areas.

The consequences for ONS.5 were immediate, and dangerous. Unknown to Winn and Beesly, hence unknown also to Horton and Gretton, on 27 April BdU established Gruppe Star (Starling), consisting of sixteen newly assembled boats, along a north-south patrol line, or “rake,” at 3o°W between latitudes 61°5o’ and 57°oo’N about 420 nautical miles east of Greenland. On the Kriegsmarine grid chart the new patrol line ran from AD 8731 via AK 3523 to AK 0329. The boats were to be in place by 0900 GST on the 28th.20 The line’s northernmost wing just brushed the course of ONS.5. At 0800 on the 28th the convoy was at position 61°45’N, 29°ii’W, turning southwest. By 0800 the next day it would pass through 30°W to 34°51’W.21 Group Star had been created expressly to catch the next westbound ONS convoy departing on the eight-day cycle, which was ONS.5.

Winn and Beesly were unable to recommend evasive routing because the order creating Star, unknown to them, went out the day after GC&CS’s reading of naval Enigma ended. Commander Gretton could not have had that piece of information. Nor could he have known that while GC&CS’s eyes were shut, the eyes of B-Service were still open. The German radio monitoring and cryptographic service was reading, though not always in real time, the Anglo-American Naval Cipher No. 3 used for convoy routing. The encrypted transmissions included the daily Admiralty or USN U-Boat Situation Reports (which should have been another clue to BdU that its own cipher had been compromised).

When data from B-Service on the composition, sailing date, course, and speed of a convoy reached the green baize table in BdU’s situation room in Berlin/Charlottenburg, it was assigned a number. Convoy ONS.5 was assigned No. 33. We do not know the exact form in which information about ONS.5 was first communicated to BdU because that daily or hourly message traffic no longer exists; but the B-Service’s extant summary for 26 April—2 May discusses the convoy by name in connection with both the Third Escort Group (EG3), which will appear as a Support Group for ONS.5 later in this narrative, and a USN U-Boat Situation Report:

“The Third Convoy Escort Group was positioned at 47°2o’N, 50°03’W on 29 April at 2100, course approximately 100°-200°, speed 15 knots, heading toward ONS.5; it should have changed course at 47°oo’W by 11–13 degrees. The American U-Boat Situation Report of 30 April identified up to 20 boats in the general area 59°61’N, 30°43’W as a result of various wireless direction finding methods, and that a few of those boats continue to be positioned near ONS.5.”

From this entry it is not possible to pinpoint the day when ONS.5 was first identified to BdU. The dates given, 29 and 30 April, relate to events reflected on after a week’s decryption effort. Was word of ONS.5 passed to BdU as early as 26 April, when the week began? We may never know the answer. What is known is that in establishing the position of the Star line, the BdU war diary of 27 April stated: “The object of this is the interception of the next ONS convoy at present proceeding in the North…. A slow southwest-bound convoy is expected there on 28 April.” Advantage: Germany.

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At 0900 on the 28th, a time when some late-arriving boats were still maneuvering to their Star stations, Oblt.z.S. Ernst von Witzendorff had U—650 on the surface in naval square [qu] AD 8761. Conditions were a moderate sea, wind from the southeast Force 3, and visibility 12 nautical miles. One of the lookouts with binoculars on the conning tower bridge sighted, “Mastspitzenn!” Von Witzendorff wrote in his KTB: “Mastheads sighted. I am closing them to see what we have. It’s a convoy proceeding southwest.” At 0942 he transmitted an Ausgang F. T. (outgoing wireless message) to BdU: CONVOY AD 8758. Seventeen minutes later he sent again: CONVOY STEAMING AT 8–10 NAUTICAL MILES, COURSE 270°. At 1040 Witzendorff was heartened to see another U-boat of Group Star surface a short distance away on the port side. Three minutes later, he received a message from BdU directed to all Star boats: GROUP STAR SHOULD ATTACK ON BASIS OF WITZEN-DORFF’S REPORT. WITZENDORFF IS FREE TO ATTACK AS SOON AS ANOTHER BOAT HAS CONTACT. At 1110 U-650 updated her first report: WESTBOUND CONVOY NOW IS AD 8728, SPEED 8 KNOTS.

The IIIO transmission was picked up and DFed by HMS Duncan and HMS Tay, as well as by escorts supporting eastbound Convoy SC.127, about 60 nautical miles due south of ONS.5.24 Gretton now knew that ONS.5 was being shadowed—but on behalf of how many boats? He sent the corvette HMS Snowflake to search down the bearing for the transmitting U-boat, which Gretton calculated, based on its strong signal, was “close ahead.” Meanwhile, he altered course of the convoy 35 degrees to starboard and maintained 296° until 1600, when he returned to the original course. Snowflakes search was fruitless, as was a ten-mile high-speed sweep ahead of the convoy by HMS Duncan. Visibility declined to three miles.

At 1650 a U-boat signal detected from astern at 085 degrees indicated that the course alteration, which placed ONS.5 north of the Star rake, had been successful, for the time being. HMS Tay hunted down that bearing and HMS Vidette tracked another, but made no contact. Gretton worried that the U-boat shadower was part of a large pack—one wholly unanticipated—and that it would not divide its forces between his convoy and SC.127 but concentrate them solely on him, and at night, when the U-boats had 17–18-knot surface speed. As dusk came he worried, furthermore, that he could expect no help from aircraft. The air escort given ONS.5 from 24 April had been discontinued at midnight on the 27th/28th, since there were no OIC reports of U-boats in the vicinity. The convoy had been sighted in the late afternoon by a distant USN Catalina, but the possibility of air cover this night, if requested, was remote, since Iceland was socked in by weather.

At 1838, as a heavy head sea formed, HMS Duncan DFed a U-boat close on the port bow, bearing 210°. He chased it at maximum speed and ordered HMS Tay to make a parallel search to port. At 1920 HMS Duncans bridge sighted a cloud of spray thrown up around a U-boat’s conning tower, about two miles bearing 146°. Gretton altered course to pursue the boat, but at a range of about 3,000 yards it dived. In the rough sea HMS Duncan’s asdic failed to make contact, but Gretton fired a ten-charge pattern of D/C by plot. HMS Duncan and HMS Tay then carried out operation “Observant” for an hour. Observant was an asdic square search of two-mile sides with the “Datum Point” (contact point) at the center; one of the escorts could either reinforce the square (sometimes called box) or operate within it. Leaving HMS Tay to sit on the submerged boat while the convoy passed, HMS Duncan returned to establish night stations with the convoy at 2130.25The merchantmen, now beginning a southwest leg, were on course 240°, speed 7.5 knots. The wind was freshening from the southeast at 16–20 miles per hour and the sea was rough, with moderate long swell.

Knowing that U-boats preferred to attack down sea, so that spray did not betray their approaches, and knowing, too, from HF/DF that the U-boats were on the port bow beam, and quarter, and astern, Gretton “placed his field” with strength to that side, leaving the starboard bow uncovered. Attack abaft the port beam was most probable. Where the Germans were concerned, by nightfall only four of Star’s other U-boats had rallied to U–650’s reports: U-386, U-378, U-532, and U-528. That more had not assembled on the convoy’s course, despite BdU’s urging to do so, was owed in part to the “hazy weather” and “strong wind” against which the boats “had to struggle during their pursuit of the enemy.” This, at any rate, was the assessment of BdU on 1 May, after all the excuses were in. If only five boats were on the scene by darkness on the 28th, the rest were not unheard from, however, as every Commander made his evening position report to Berlin. The W/T traffic—“like a chattering of magpies”—was DFed in England as well as by B7’s two HF/DF sets.

For Gretton there were two immediate good results from this chatter. In view of the concentration around ONS.5, CinCWA detached destroyer HMS Oribi from the escort of SC.127 and sent her, at 20 knots, to his assistance. And since this convoy was likely to be targeted by the western U-boat packs, when it reached those longitudes a Support Group (EG3) of four Home Fleet destroyers, HMS Offa in command, was ordered to steam out of Newfoundland at 15 knots to meet ONS.28. With those pledges of reinforcement to brace their spirits, Gretton and his Captains prepared for the night battle sure to come.

In an interview conducted fifty years later, Lieutenant [now Sir] Robert Atkinson, R.N.R., Captain of the corvette HMS Pink, remembered the night of 28 April:

“Well, I remember once getting a fantastic signal. I will give you an example—in H.M.S. Pink. We were about a hundred and fifty miles west-southwest of Iceland, approaching Greenland, and there was a moonlight night—going to be a moonlight night, a very nasty night, windy. And we received a signal from the Commander in Chief [Horton]: “You may expect attack from down moon at approximately 0200.” Now they knew and were able to interpret in Whitehall [the Admiralty] the various radio activity and signals by the German U-boats—great activity. They knew where the moon would be and when it would rise and where the U-boats might attack from—he liked a profile. And by the feverish increased activity of the radio signalling, they knew attacks were imminent. Now we didn’t know that, of course, but the fact that we had a signal telling us to be ready for attack about 0200 made all the difference. And Admiral Gretton, who was Commander Gretton then, we were so highly trained he sent a signal round to our escort group, and do you know what that signal said?—one word, “Anticipate,” that’s all he said. Didn’t get excited, and didn’t tell the men.to do this, or not do the other. It wouldn’t have been any good. We were trained; we knew what to do. And do you know what I did? It was about five o’clock, pitch black, windy as hell, and I said, “Hands to tea, six o’clock.” Cleared lower deck and said, “There’s going to be a hell of a battle tonight. I’m not sure how many of us will see daylight. I intend to see it if I can.” So it was up to us.”

The night battle began earlier than Horton, or Atkinson, expected, at exactly 2358 when one of the four Star boats in the sea to port made the first of six attempted attacks that took place between that hour and daybreak on the 29th. Gretton wrote up his report of the action in unadorned telegraphic style:

"The first attempt was made at 2358, when SUNFLOWER on the port bow got an RDF [radar] contact bearing 170°, range 3000 yards. She ran out towards, but the U-Boat dived, and as no A/S [asdic] contact was obtained she dropped two charges and resumed station. TAY was in station by 0300 [29 April] and at 0045 (the second attempt) DUNCAN got an RDF contact bearing 100°—3500 yards and turned to attack. The U-Boat dived at 2500 yards and A/S contact was picked up at 1500 but almost at once lost. I dropped one charge, ran out and back over the firing position and was resuming station when at 0114 (the third attempt) I obtained an RDF contact bearing 296°—2500 yards. I chased at best speed until at 0119 at range 1100 yards, the U-Boat dived and I reduced to operating speed. RDF plot gave U-Boat’s course as 320° and at 0122 A/S contact was obtained on last RDF bearing, her wake was sighted, and an accurate ten-charge Minol [explosive charge] pattern was dropped. At 0130, while running out after this attack another RDF contact was obtained bearing 146°—4800 yards (the fourth attempt). I turned towards, chased and at 0140, the U-Boat dived at range 3000 yards. No A/S contact was obtained so one charge was dropped by plot. The chasing course was into the wind and seaspray was flying mast high and the U-Boat saw us coming earlier than when we had chased down sea.

As I was turning to resume station after this attack, yet another RDF contact was picked up bearing 210°—4000 yards at 0156 (the fifth attempt) and again I turned and chased at best speed. The U-Boat was heading for the convoy at about twelve knots, but at 0204 at range 1500 yards, he dived and I reduced to fifteen knots. At 0203, the ship passed through a patch of oil about fifty yards diameter, so this U-Boat may have been previously damaged. Good A/S contact was obtained and an accurate ten-charge Minol pattern fired. At the moment of the firing, his wake was clearly seen under the port bow. Contact was regained astern, but lost at 800 yds each time I attempted to attack, so that the idea of a hedgehog [impact-fused bombs fired forward] attack had to be abandoned. I dropped two deep charges on him by plot and resumed station at high speed. At 0054, I had ordered TAY to take position R [port quarter] in my absence. I was back in station by 0310, and TAY ordered to resume position S [astern].

SNOWFLAKE in position P [port beam] drove off the sixth attempt, at 0339, sighting a U-Boat on her port bow, range 1100 yards, steering towards the convoy. SNOWFLAKE attacked and fired two ten-charge patterns, a torpedo narrowly missing her in return. By 0348, SNOWFLAKE had dropped astern into the port quarter position so I moved up to the port beam in her place. At 0354, TAY, in position S, gained and attacked a good A/S contact—a possible but unlikely seventh attempt. By then, dawn was starting to break, and at 0416 I ordered day stations, so that ships would have plenty of time to gain bearing into the ahead stations for the expected dawn attack submerged. The night had been a busy one, the convoy unscathed, and I felt that the U-Boats must be discouraged by our night tactics and might try day attack.

It was a good night’s work for Royal Navy B7 escorts, and Gretton was elated. Against what he estimated were “five or six” U-boats the B7 team had performed splendidly. Not a single ship in the convoy had been sunk or damaged. But he was sure that the U-boats had suffered, and he was right: of the four boats that actually participated in the attacks, two, U-386 (Oblt.z.S. Hans-Albrecht Kandler) and U-528 (Oblt.z.S. Georg von Rabenau) were heavily damaged and forced to withdraw to base, though it is not possible to determine whether it was HMS Duncan or one of the corvettes, HMS Sunflower or HMS Snowflake, that was responsible for either or both. The Type VIIC U-386 limped into home port at St.-Nazaire on 2nd May. On the same day, the Type IXC/40 U—528, also struggling to return from what was her first combat patrol, was approaching the Bay of Biscay when she was located , bombed and badly damaged on the surface by a radar equipped Halifax II bomber “D” of 58 Squadron from RAF Coastal Command and then she was finished off by two Royal Navy escort ships , the destroyer HMS Fleetwood and corvette HMS Mignonette, escorting nearby convoy OS.47. Both Royal Navy escort ships were vectored from the convoy to the location of U-528 by Halifax bomber aircraft and they located submerged U-528 with a through sonar sweep and then HMS Fleetwood fatally damaged German U-Boat with a prolonged depth charge attack. When U–528 had to surface to avoid sinking both HMS Fleetwood and HMS Mignonette located , hit and sank her with gunfire with the loss of eleven killed, forty-five captured (picked up by Royal Navy escort vessels) from U-boat. Gretton certainly thought he had a kill on the third U-boat attempt, which he called “an accurate attack,” and this may have caused damage to one of the two boats cited. In any event, it was, as he said, “a most successful night.”

On her maiden escort with the Group, HMS Duncan had detected and attacked four separate U-boat advances in the space of one hour and fifty minutes, and in weather conditions where the ship was pitching and rolling wildly, and seas washing down the quarter deck made the work of loading and reloading the heavy D/Cs both difficult and dangerous. Gretton used the loud-hailer to praise the behavior of his ship’s company during their first baptism of fire. The two corvettes had also given a good account of themselves, although each committed an error: In dropping two D/Cs at 2208 to scare off any U-boats in her vicinity, HMS Sunflower inadvertently dropped a calcium flare that lit up the entire seascape—“rather an unnecessary advertisement,” as her Canadian Captain, Lt.-Cmdr. J. Plomer, R.C.N.V.R., dryly put it. HMS Sunflower turned back to extinguish the light and, on a second attempt, by going hard to starboard, drew it through the propeller stream.

HMS Snowflake had a dicier experience, which Gretton called “an unusual slip in the drill.” During the sixth U-boat attack, HMS Snowflake followed a radar contact at 0332 and sighted an approaching boat in the process of diving. When about 200 yards astern of the boat’s swirl, the wheel was suddenly put hard-a-starboard, though no such order had been given. As a result, the U-boat passed on a reciprocal bearing 200 yards down the port side and no D/Cs were fired. HMS Snowflake’s Captain, Lieutenant Harold G. Chesterman, R.N.R., dropped three D/Cs between the U-boat and the convoy as scare tactics. At 0336 he gained an asdic bearing at range 2,000 yards and turned to the attack. As he did so, at 0338, ship’s hydrophone first detected, then lookouts sighted, a torpedo pass 20 yards down the port side.

This was the only torpedo seen the night of 28th/29th. It was launched by U-532 (Korv. Kapt. Ottoheinrich Junker), but it was not the only eel in the water. Just three minutes before, by periscope, Junker had launched a four-torpedo Fächerschuss (fan shot) from his bow tubes at what he called “the third steamer” in a column, estimated by him at 5,000–6,000 GRT. All the eels missed. The depth of run was three meters, which should have been shallow enough to hit a ship even in ballast. Seven and a half minutes later, Junker would hear end-of-run detonations. Meanwhile, using the two stern tubes that a Type IXC/40 boat commanded, he got off a double launch against HMS Snowflake (only one of which torpedoes was sighted), missing again, as already noted, and hearing end-of-run detonations seven minutes later.

Junker states in his KTB (war diary) that as he placed the escort in his crosshairs, he could see convoy steamers in the background. His six misses in that crowded seascape were perhaps ineptitude, or just bad luck. The fault could not have been inexperience: the thirty-eight-year-old native of Freiburg im Breisgau had commanded U-boats since 1936, though it bears mention that he did not have a single ship to his credit. With U-532 having to reload all tubes, the initiative now passed to HMS Snowflake, which Junker’s periscope displayed steaming toward him at high speed, only 1,200 meters distant. “Alarm!” his KTB records, as U-532 opened flood valves and dived to greater depth—and just in time, as HMS Snowflake dropped a ten-charge pattern over him at 0343. When the noise and turbulence subsided at 0345, HMS Snowflake regained asdic contact. With the recorder marking well, Chesterman came round to port, and at 0351 fired a ten-charge pattern set to 100 and 225 feet. This second attack, Chesterman noted, “is considered to be accurate.” Then, with only “doubtful” asdic contact showing on the recorder, and concerned that he should husband his D/Cs remaining for battles to come, Chesterman shaped course to rejoin the convoy.

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Deeper than 225 feet, U—532 was still alive, but wounded. Junker wrote in his KTB:

“The entire hull of the boat vibrated violently. Before each depth-charge series we could hear the asdic sound pulses [Ping-tongg! Ping-tongg!]…. We found major damage done to the forward hydroplanes. They ran quite laboriously and made strong knocking noises. They tended to stick in the “hard up” position, but could be freed again. For the time being we are limiting them to “up 15°“…. A large number of manometers, lamps, and electrical equipment have gone out, though without any restrictive effect on the boat’s operation…. Battery array No. 1 was badly cracked, with the result that acid leaked into the bilges…. The magnetic compass broke, which is a nuisance because, unable to use the noisy gyrocompass when in creep, or stalking speed [Schleichfahrt, about 2.5 knots] we have no means for checking the course of the boat…. I don’t want to end up running into the hands of the enemy.”

Junker records that he remained submerged, experiencing or hearing various series of D/Cs—five more ten-patterns—“additional series or single drops”—“new depth charge attacks”—“three more series”—as far as 0140 (2340 GMT on the 29th) on 30 April, when he surfaced, the last hours having been spent breathing through potash cartridges because of the 3 percent level of CO2 in the boat. Troubled by intolerable noises inside the boat, he set course back to base. The BdU gave U-532 credit for “two hits” and duly noted the boat’s ordeal: “She was hunted for fifteen hours.” The problem with the fifteen-hour story is that the D/Cs heard by U-532 after HMS Snowflake s two drops were not meant for her but for the U-boat involved in the McKeesport event, described below. The sum of U—532’s patrol was: no hits, six misses, and one badly bent boat forced back to base.

The BdU did not learn of U-532’s alleged hits until 2 May. At the time of the night battle it was dismayed that not a single Treffer, or hit, had been scored. In rationalizing the failure, it argued first that the boat’s messages to Berlin were inaccurate. They overestimated the convoy’s speed—certainly that was the case with U-650’s initial estimates—and the reports from U-386 and U—378 on the enemy’s position were too far distant from each other to make any sense. Second, atmospheric or magnetic interference apparently was preventing BdU’s operational orders from getting through, since no acknowledgments were coming back, and no messages of any kind were received from the boats during the period from 0300 GST on the 29th to 1200 on the 30th. Third, Force 6 winds, heavy seas, and limited visibility greatly hampered surface operations.36 For the first time in a long while, Admiral Dönitz’s command and control system had been frustrated and bootless on the night of the 28th/29th. But an enterprising individual commander, operating on his own initiative, could break the string.

In the early daylight of the 29th, fulfilling Gretton’s expectation that, unable to overcome B7’s night tactics, the U-boats might try submerged attacks in daytime, U—258 (Kptlt. Wilhelm von Mässenhausen) slipped inside and under the convoy formation, where he took a position at periscope depth starboard of the convoy’s No. 4 column. In doing so, he somehow avoided the asdic sweeps by the escorts on day stations as well as by Tay, which was searching astern for damaged or shadowing boats, and by Vidette, which returned to her station at 0725 after searching out 15 miles. It was broad daylight. At exactly 0729 1/2, the furtive U—258 scored a hit on the 6,198-GRT American Moore-McCormack freighter McKeesport, ship No. 42, the second ship in No. 4 column, which was on a return voyage from having delivered to Manchester, England, a cargo of grain, steel tanks, foodstuffs, and chemicals.

Gretton was asleep in his sea cabin when the alarm bell rang. Dashing to the bridge, he ordered “Artichoke” at 0730. In this operation the ship in position “S,” astern, closes the torpedoed ship at maximum asdic speed, and ships in the “forward line,” that is, “A,” ahead, “B,” starboard bow, and “L,” port bow, turn immediately outward to a course reciprocal to the course of the convoy and sweep in line abreast at 15 knots or at the maximum asdic sweeping speed of the slowest ship, the wing ships passing just outside the convoy wake, the inner ship(s) between the columns of the convoy, until reaching a line 6,000 yards astern of the position the convoy was in when the ship was torpedoed. All other escorts continue on the course of the convoy.

Five minutes later, Gretton saw a torpedo, which had passed through several columns without a hit, explode at the end of its run on the convoy’s port quarter, indicating an attack from starboard, probably along 180 degrees. The rescue trawler Northern Gem acquired an asdic contact astern of McKeesport and made an attack with three D/Cs. There was no result. And an “Observant” carried out by Duncan proved fruitless. Admiringly, Gretton called U—258’s action “a bold effort,” and, what was more, the attacker got away—for now.

On board McKeesport the torpedo’s explosion had come as a complete surprise. The Chief Officer, Junior Third Officer, and two seamen-lookouts on the bridge made no periscope sighting. Neither did the U.S. Naval Armed Guard who manned a four-inch gun on the afterdeck. Nor did the seaman-lookout on the fo’c’s’le, although on the starboard side he did see a long, dark, round object leap across a trough of the choppy sea, which he thought was a fish. He correctly identified a second torpedo that ran astern, but it was too late to warn about the first. When the warhead detonated with an awesome bang, it not only shook the whole ship; it opened a hole at the collision bulkhead of No. 1 hold, which, like holds 2, 3, and 5, was filled with sand ballast; put the steering apparatus out of order; flooded the forepart up to tween decks; and twisted plates, beams, and hatches. Fire spread through wooden grain fittings, but the inrushing sea put it out.

McKeesport lurched to port, causing the British Baron Graham on that side to consider evasive action. Incredibly, the listing merchantman maintained convoy speed in her station for fifty minutes, until, with her engine room flooding, she started to sink at 0815, and the Master ordered Abandon Ship. Life nets were thrown over the side and the boats were lowered. Unfortunately, the boats became entangled in the nets, and so did some of the men who used them to climb down to rafts. Several seamen fell into the water, one of whom would later die from exposure, the only fatality from McKeesport’s complement. Last to leave were the Master and the crew of the Naval Armed Guard, under command of Ensign Irving H. Smith, U.S.N.R., who gallantly stood by their gun until ordered to leave. The rescue ship Northern Gem came alongside and picked up the survivors: forty-three seamen, one critically injured, and twenty-five naval crew.

While the Master had cast overside his Confidential Books, including his codes, in a weighted container, he had neglected to jettison his ship’s log and charts, on which future rendezvous positions were marked. Accordingly, Northern Gem made an effort to sink McKeesport with her ship’s gun, but the derelict ship remained afloat. It was U.S. Navy Department policy, stated by Secretary of the Navy Frank Knox on 30 March 1942, that “no U.S. Flag merchant ship be permitted to fall into the hands of the enemy.” Since that was the policy and McKeesport could be boarded by a U-boat crew, Gretton ordered HMS Tay to go back and hole the wreck, which she did with depth charges.

The steel shell went down with all her relics of human habitation, including eight decks of playing cards and other games: cribbage, dominoes, checkers and acey deucy, as well as sports equipment: darts, deck tennis, two pairs of boxing gloves, and one medicine ball; and divertissements: one portable radio, one Victrola, and twelve records. The Master had no complaint about his escorts. The sinking was, he said, “just one of those things.” HMS Tay then pursued a U-boat contact 49 miles astern and did not rejoin B7 until 0600 the next day, the 30th. At 1100 that morning the convoy half-masted colors for the burial at sea of McKeesport’s lone fatality, John A. Anderson, a Swedish national, who had died on board Northern Gem.

No attack on ONS.5 developed during the night of the 29th/30th April, although HF/DF and asdic contacts led HMS Duncan and HMS Snowflake to drop “scare tactic” charges. The destroyer HMS Oribi, homed from astern by HF/DF, arrived during the night, at 0100, from EG3. In the southwesterly wind and sea she had only been able to make II knots.40 Her HF/DF equipment (Type FH3) lent additional detection ability to the screen. Coastal Command, alerted to ONS.5’s peril on the 28th but delayed by weather conditions at 120 Squadron’s air base at Reykjavik, finally was able to reestablish air contact when a VLR Liberator arrived overhead the convoy at 0645 on the morning of the 30th. Soon afterward, however, owing to a drop in visibility, the aircraft returned to base in Iceland.

The U-boats would remain at bay all that morning, and at 1045, the short-legged HMS Oribi took advantage of the respite to oil from British Lady. Unfortunately, the destroyer, which was unaccustomed to refueling at sea, fouled the oiler’s gear. That fact, plus a new deterioration in the weather that had already been, in Gretton’s words, “astonishing even in the North Atlantic,” made it impossible for other escorts to top up—with ultimately grave consequences for HMS Duncan. By 2100 another gale was blowing from ahead, the wave heights were rising steeply, and the escorts were rolling gunwales under.

At 0105, in the first highly visible sign that some of the U-boats had maintained contact during the past forty-one hours, HMS Snowflake acquired a U-boat’s radar signature at 3,300 yards, ran down the bearing, fired a starshell at about 10 o’clock three miles from convoy, sighted the boat at 3,000 yards, fired “near misses” at her with both the four-inch deck gun and 20mm Oerlikon anti-aircraft (AA) guns at maximum depression, and forced it to dive. To discourage it further, HMS Snowflake dropped a D/C on the swirl—which was a hazardous thing to do given the rough sea, which prevented an attacking ship from getting much beyond the blast effect—as HMS Duncan discovered himself when he dropped two on another contact at 2345: with maximum speed up sea only 8 to 9 knots, the D/C pressure waves lifted his stern clean out of the water, opened leaks, and, what was worse, smashed all the gin glasses in the wardroom. There were two other “scare tactic” D/C drops that night, and no general attack on the convoy developed.

The morning weather on 1 May was atrocious. By afternoon a Force 10 gale was dead in the convoy’s teeth, preventing all but the most modest progress forward. Convoy speed was 2.7 knots and dropping. In the tempest, columns as well as ships within columns separated from each other. Commodore Brook’s log noted: “Half convoy not under command, hove to and very scattered.” Gretton, whose Duncan was hove to with winds pushing alternately against one bow and then the other, marveled that an entire convoy could be brought to virtually stationary condition. On Pink, Lt. Atkinson placed a chair on the raised platform at the fore part of his open bridge and went into half-sleep, rocking with the motion of the corvette. Nearby were a gyro compass and voice pipes to helmsman and navigator. Compass repeaters were on both wings port and starboard. Ahead and several feet below was the asdic hut (or office). Aft and a deck lower was the helmsman. On the port quarter of the bridge was the tall radar hut (office, house). Aft of the bridge were the ship’s mast and funnel. For protection against the cold gale Atkinson wore a heavy sweater, a cloth, not very warm, duffel coat with hood, a Balaclava helmet (knitted wool head sock), naval cap, seaboot stockings, and mitts. Like the rest of the crew, he was the recipient of wool clothing articles knitted by women volunteers in Australia, New Zealand, and Canada, with whom correspondence was exchanged and lifelong friendships forged.

Aircraft flew over the dispersed merchantmen during the day, including two RAF VLR Liberators from 120 Squadron in Iceland who gave valuable assistance by identifying the positions of stragglers, and by warning of icebergs, growlers, and pack ice starting thirty miles ahead. Less helpful were two U.S. Army B-25 Mitchell bombers from Ivigtut, Greenland, which made no contact whatever with the convoy either by wireless (W/T), voice radio (R/T), or light signals (V/S), although one of them, as Gretton learned later, made an unsuccessful attack on a U-boat some 60 miles to the south; and one of them further helped to confuse BdU by forgetting to switch off its navigation lights: The flashing beacons, which, of course, announced the bomber’s position and course to any U-boat that might be watching, caught the attention of U-381 (Kptlt. Graff Pückler), which at once signaled BdU about an apparent secret weapon. In Berlin, where Grossadmiral Dönitz and Konteradmiral Godt were at this time unusually accommodating of the notion of secret devices, the BdU war diary for 1 May noted: “The [U-351] observed what was probably a new type of location gear. The Commander repeatedly noticed planes approaching at great height and carrying a light like a planet that went on and off.”

What is more interesting to learn from the 1 May diary entries concerning convoy “No. 33” is that BdU decided that with only six of sixteen Star boats reporting contact with the convoy, the rest having failed to gain purchase, with three survivors of those six now submerged to avoid both the weather and the aircraft, and with so little to show for four days’ effort, further pursuit of ONS.5 was not worth the candle. At dusk the longwave antenna array at Calbe, 43 kilometers south of Magdeburg, sent the order, which could be heard by the submerged boats to a depth of 25 meters: break off the operation. BdU’s rationalization of the failure read: “This attack failed only because of the bad weather, not because of the enemy’s defenses.” No doubt a different appreciation of the battle was entertained on the bridge of HMS Duncan.

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By dawn the next day, the weather had moderated somewhat, and the speed of the convoy was back up to 5 knots. During the previous twenty-four hours only 20 miles had been made. Gretton and his escorts took advantage of the settling seas to round up stragglers, of whom there were many, some at a distance of 30 miles from the Commodore. In this B7 and HMS Oribi were helped by a VLR Liberator from the Reykjavik squadron that flew over 1,000 miles to assist in locating ships. Eventually, most of the flock was gathered, except for two parties taken under charge by HMS Pink and HMS Tay some miles astern, and two laggards that peeled off to sail independently. In the forenoon of 2 May, Gretton and Brook began negotiating the first ice pack on their route. Small growlers and floes now became the hazard rather than high seas. HMS Duncan thought this a good time to top up from British Lady, but the oiler’s constant alteration of course to avoid the ice made the maneuver impossible; and by the time ONS.5 was clear of ice the wind and sea were making up again from the west-southwest, frustrating Gretton once more.

In the evening B7’s transmitters vectored in the EG3 Support Group destroyers of Home Fleet, HMS Offa, HMS Penn, HMS Panther, and HMS Impulsive, which joined at 2040. Unfortunately, like HMS Oribi, these were all short-legged ships that had expended a good amount of their fuel making rendezvous. Gretton’s HMS Vidette was the only destroyer in the enlarged screen that had been designed for or, as was the case, modified for long-range escort duty. There was a brief awkward moment when Gretton, who was junior in rank to the Support Group senior officer, Captain J. A. McCoy, R.N., in HMS Offa, “made requests of” (gave orders to) his senior in grade; but Gretton found McCoy more than willing to accept the subservient role, and very friendly in his cooperation.

That night McCoy’s ships took up extended screen stations assigned to them by Gretton, which changed from first dark to midnight, from midnight to dawn, and from daybreak to sunset. There was no sign of the enemy during the night, and the morning of 3 May was similarly quiet, except that gale-force winds from the southwest continued to howl around the main body of the convoy, which now numbered thirty-two ships together. The close escort and support ships spent the forenoon searching for stragglers.

Gretton exempted himself from that labor and crawled ahead at convoy speed, anxious about his fuel remaining, and deciding what to do about it. Because of the still heavy seas, topping up from British Lady was out of the question; and the weather forecast did not allow for any calmer surface ahead. What oil he had left in his bunkers was sufficient to make Newfoundland only at economical speed. If he stayed with the convoy, the likelihood was that he would go dry and have to be towed. If the enemy was still in touch, his powerless ship would invite easy attack. As for transferring his command of B7 to another ship and sending HMS Duncan and her crew to St. John’s, that, too, was not an option: the appalling weather made transfer by boat or jackstay impossible. So HMS Duncan would have to go, and Gretton with her—at a time, he grieved, when ONS.5 was still in jeopardy, and just at the beginning of a story that Gretton later would describe as “probably the most stirring of convoy history.”

At 1600, by R/T, he handed over command as Senior Officer Escort to Lt.-Cmdr. Robert Evan Sherwood in Tay, changed course, and proceeded at best economical speed, which was 8 knots, toward St. John’s. Though emotionally depressed—“thoroughly ashamed of ourselves,” he would say—Gretton understood rationally that the reason for his withdrawal lay not with any inadequacy of himself or his crew, but with the Royal Navy strategists and engineers who decided in the 1920s what ought to be the fuel endurance of a destroyer. In fact, that night and the next morning three destroyers of the Support Group similarly left the convoy because of fuel depletion, first HMS Impulsive to Iceland, then HMS Panther and HMS Penn to Newfoundland. Also, on the 4th, Sherwood detached Northern Gem with her McKeesport survivors to Newfoundland. And at the same time, he signaled CinCWA that unless the weather cleared enough to make oiling from U.S.S. Argon practicable, he would have to detach destroyers HMS Offa and HMS Oribi no later than Wednesday morning the 5th.

Helped by unexpectedly fine weather and a boost from the Labrador Current, a disappointed HMS Duncan made St. John’s with four percent of fuel remaining. Left behind in the sea lanes was a severely diminished convoy escort with four of its once seven-strong destroyer force already removed from the screen, facing now the threat that it would lose two more destroyers on the morrow. That would leave ONS.5’s escort a predominantly corvette force. And at just this juncture HMS Tay’s asdic went out and was pronounced irreparable.

But the new commander Sherwood had at least three reasons for optimism: for one thing, CinCWA ordered First Escort (Support) Group at St. John’s, consisting of the Egret class sloop HMS Pelican; Commander Godfrey N. Brewer, R.N., Senior Officer; the River Class frigates HMS Wear, HMS Jed, and HMS Spey; and the ex-U.S. Coast Guard Lake class cutter HMS Sennen, to “Proceed at best speed through position 47 North 47 West and thence to reinforce ONS.5”; for another, the winds subsided to Force 6 and the seas abated somewhat, with the result that convoy speed advanced during a twenty-four-hour period from 3 to 6 knots; and, for still another, ONS.5 incredibly had passed through most of the dreaded Greenland Air Gap without sustaining a single attack.

Yet 4 May was a day when lifted spirits also had their troughs: HF/DF receptions, which had been for a while still, became active again and gradually increased in number, indicating to Sherwood that U-boats, whether from the last group or from a new one, were reacquiring contact from port bow and beam. Convoy ONS.5 was not yet beyond jeopardy.

Sherwood’s credentials for leadership were longstanding and well-tested. At sea since 1922, when he served with the Merchant Navy, he joined the Royal Naval Reserve in 1929, became a sublieutenant in minesweepers, and served nine months on the battleship HMS Warspite. While continuing a member of the reserves, he resumed Merchant Navy duties with Holyhead-Dublin steamers until the outbreak of war, when he took an asdic course, spent a short stint with the Dover Patrol, and transferred to corvettes, assuming command in 1940 of HMS Bluebell, among whose fifty-two-man crew he found only three or four who were “capable of any real action of any kind at all.” In time he trained them to a high degree of seamanship and technical proficiency, and of himself he said that it was good training to have held command early of a vessel as difficult to handle as a “Flower” class corvette, a ship type that struggled against every wave and swell. HMS Bluebell, he said, “would do everything except turn over.” Advanced to command of HMS Tay in 1942, he was assigned to Gretton’s escort group, with which he captained the first ship on which B7’s Senior Officer Escort embarked.

Described as being of medium height and stocky build, Sherwood framed bright, humorous eyes within a full naval beard. Not very well spoken, one of his fellow Captains said of him, and lacking in the kind of presence that Gretton generated, he was nonetheless a fine seaman whose command decisions were swift and firm. Though he was a reservist and lower ranking than Gretton, the Support Group regulars accepted his orders. On every fighting bridge there was confidence that Sherwood had mastered Gretton’s painstaking game plan of search and sink. Now, as ONS.5 groped toward the unknown, with HF/DF contacts growing more numerous, and with all the original B7 group that remained damaged and worn by bitter weather and a running fight, it would take all of that mastery to see the convoy into port. Sherwood’s concern would have been all the greater had he known that fewer than 70 nautical miles dead ahead as large a wolfpack as any of the war would assemble to meet him.

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5 COLLISION OF FORCES

The Battle for ONS.5

And two things have altered not
Since first the world began—
The beauty of the wild green earth
And the bravery of man

T. P. CAMERON WILSON

THE DESTROYER, WITH ITS SPEED, armament, maneuverability, and capacity to keep the sea, was the traditional and deadly enemy of the submarine. The even better ASW vessel, the destroyer escort, was not yet available in numbers from American yards, where volume construction began in April. Much good could be said as well for the performance to date of the “River” class frigate (301’6” long overall, displacing 1,370 tons, speed 20 knots) and the “Black Swan” class sloop (299 feet long overall, displacing 1,300 tons, speed 19¼, knots). But the surprise of the ASW war was the smaller and relatively slow “Flower” class corvette (205 to 208 feet long, displacing 950 to 1,015 tons, speed 16 knots). These perhaps most famous of British ships of the war—fame engendered in great part by the fictional corvette Compass Rose in Nicholas Monsarrat’s novel The Cruel Sea—owed their name to World War I “Flower” class sloops that were based on a whale-catcher design and used in that conflict for minesweeper and utility duty.

Their namesake successors, produced originally by the same yard, Smith’s Dock Company at Middlesbrough, and designed by the same naval architect, William Reed, were produced, beginning in 1939, for minesweeping and ASW work in the North Sea and Channel. Their immediate ancestor was Reed’s and Smith’s Dock Company’s commercial whaler Southern Pride, whose specifications were closely followed, though somewhat enlarged, because of that craft’s ability to keep the sea. In adapting for naval use an already existing mercantile vessel design, and one that was simple to construct, the Admiralty ensured that the new single-screw “Flower” class “corvettes,” as they were to be known, could be produced in non-naval yards throughout the U.K. Altogether 221 “Flowers” and “Modified Flowers” would be built in Great Britain and Canada. (Only one “Flower” exists at the date of this writing: HMCS Sackville, launched in 1941, which helped to escort convoy ON.184 during the fateful month of May 1943; fully restored, she is on display at the Bedford Institute of Oceanography , Nova Scotia)

Corvettes, which, as Monsarrat wrote, “would roll on wet grass,” were not designed for deep ocean work, but that, ironically, became their primary service as Britain desperately sought escorts for her trade lifeline, and “Flowers” accompanied all but one of the non-carrier-escorted HX, ON, ONS, and SC convoys that crossed the northern sea lanes during the months of April and May. Though well proven as seaworthy in midocean escort, the corvettes’ lively dipping and wallowing in heavy seas placed a pronounced strain on ships’ companies. Said seaman Cyril Stephens of HMS Orchis: “Sick … yes, that was the first baptism of a corvette…. It was like a corkscrew. About the third dip and you’d get tons and tons of water come over the fo’c’s’le…. You had wet clothes on steam pipes trying to dry, you had water floating around all over the place, people being sick…. It was awful.”

Not restricted to courses that headed into heavy seas, to avoid damage or capsizing, as was the case with built-for-speed destroyers, the corvettes could show their broad beams to hard seas with ease and confidence. Not given to slamming, either, as destroyers were want to do in sea states of 5 and upward, the early short-forecastle corvettes did pitch and heave violently, and it was the resulting vertical acceleration that caused seasickness—in combination with poor ventilation, a dank ambiance, and the unbalanced diet of RN messing. As naval architect David K. Brown pointed out recently, vertical acceleration, which varied linearly with wave height, also led in its severe phases to impaired judgment and performance, hence impaired fighting effectiveness (although Sir Robert Atkinson, who commanded Pink, told the writer that he experienced no such adverse mental effects). In an attempt to resolve that problem, later ships of the original class were given a lengthened forecastle deck, extra sheer and flare to the bows, and various bridge improvements. The short length of the corvette had one advantage, and that was a small turning circle, assisted by a good-size rudder in the propeller wash, that enabled the ship to get her stern quickly over a submerged U-boat contact.

The number of D/Cs carried on board increased during the war from twenty-five to fifty. Crew numbers similarly increased, from twenty-nine to over eighty. Endurance was rated at 3,850 miles at 12 knots on 233 tons of fuel, the average convoy run being 3,000 miles, though actual endurance was uniformly less. Throughout the war corvettes appeared in the so-called Western Approaches camouflage scheme, which was an all-white ship that merged with the skyline, on which were painted panels of light sea blue or light sea green that blended with the sea. The flower names that adorned these vessels occasioned some ribaldry among seamen in larger RN ships, but no one could doubt the stamina, fighting spirit, or comradeship of the men who sailed in them.

Howard O. Goldsmith was Leading Sick Berth Attendant on HMS Snowflake:

“I suppose the nearest thing we ever came to was on ONS.5. We had probably the worst trip weather-wise of any…. There were times there when the convoy was literally stationary because some of the merchant ships just couldn’t make headway against the wind and the sea. And although the engines were turning, the screws were turning, we were just sitting there stationary. And to give you an idea of what it was like, the upper deck was out of bounds. The skipper put the upper deck completely out of bounds. The only people allowed above decks were the bridge crew, and they were told to use the Captain’s companionway, which was inboard, to get to the bridge, otherwise out of bounds completely. This seaman was a Newfoundlander who’d been brought up on schooners, and he said, “Well you don’t get weather like this every day. I’m going up the mast, see what it’s like.” And he did, he went to the top of the mast in that sea, right to the cross trees, above the crow’s nest. And when he came down he said when we were in the trough he couldn’t see over the top of the waves. So he was talking, what, seventy foot waves, that’s big. And we had this for the whole trip…. The damage to the ship was incredible. People don’t realise the tremendous power of the sea, unless you’ve seen what it can do. But I mean, for instance, all the fo’c’s’le stanchions, which were inch-thick iron stanchions, carrying the guard wires round the fo’c’s’le, they were all bent at right angles to the deck. They’d just been as though a giant hammer had hammered them over to a right angle. One ship’s boat had completely disappeared. One was stoved in. Just the waves had stoved it in, smashed it in. We used to have meat lockers which were welded to the deck. They were on the upper deck to keep the meat fresh, no fridges, you see, and they were welded on the deck and to a superstructure above the deck, welded top and bottom, with wire mesh sides to them, so that the air could flow through, and after that storm, not only had they gone, all the meat had gone, and there were just the weld spots on the deck and above, that’s all that was left. That’s just the force of the wind, the force of the sea, carried all that away. Deck lockers that were bolted and welded down just disappeared, just went, we never saw them go. Incredible power”

What now if the power of wind and seas, which B7 and ONS.5 thus far had managed to survive, was replaced by the power of a U-boat armada the size and threat of which were as formidable as any in the history of submarine warfare? At the same time that Sherwood and his convoy were edging past what was left of the Air Gap, Dönitz and Godt, prompted by the failure of Gruppe Star, were ratcheting up the offensive by combining Stars boats with those of the western Group Specht.5 Indeed, Star’s thirteen boats, including some replacements (U-7/0 having been sunk, and U-386, U-528, and U-532 having withdrawn with damage), proceeded south-southwest through the Air Gap alongside and past ONS.5, to the convoy’s east. BdU’s original intent was to have Star join Specht’s seventeen boats in stalking eastbound Convoy SC.128 (BdU’s convoy No. 34), which had departed Halifax on 25 April and was steaming on a northerly course to the west of Specht. On 1 May U—628 had reported smoke clouds that BdU took to be from SC.128. Specht-was directed to chase it down, but it could not do so. It is possible that what U-628 sighted was not SC.128 but the EG3 Support Group on its passage to join ONS.5.

By 1800 on 3 May the new Specht-Star rake ran from 56°21’N, 44°35’W (on the German grid AJ 5333) to 54°57, 39°35’W (AK 4449). Boats from this formation reported seeing smoke clouds and starshells; one signaled it had been driven off by a destroyer. The supposition in Berlin was that these boats were in contact again with SC.128. With a note of frustration, if not desperation, BdU signaled: DO NOT HOLD BACK…. SOMETHING CAN AND MUST BE ACHIEVED WITH 31 BOATS. Berlin estimated that the convoy was steaming on a course between 20° and 50°. But it was not. While some of its escorts took a course northeastward, firing starshells to draw off the U-boats, SC.128, alerted to Specht-Star s estimated position by Canadian Naval Service Headquarters, Ottawa, which had DFed it, took a jog to the west before resuming a northerly course and then turning east above the north end of the rake. Successfully evading Specht-Star, the convoy would arrive at Liverpool on 13 May without mishap. In breaking off the hunt, BdU noted, “Most of the boats are short of fuel, and it is pointless for them to run about after the convoy.”

At the same time BdU formed Specht-Star it also augmented Gruppe Amsel, to the south, and formed it into four subgroups, I, II, III, and IV, of five U-boats each, except for I, which had six. Amsel now ran, with gaps between the subgroups, from 51°51’N, 49°05’W (AJ 7933) to 44°15’N, 39°35’W (BC 9646). In a revealing comment about BdU’s awareness of the Allies’ shore-based HF/DF capability, the Berlin war diary observed: “This new type of disposition should avoid the drawbacks that arise when a patrol remains in one place for a long time so that it is D/Fed, sighted, located, etc. by the enemy, who thus finds out its entire extent.” The boats at the extreme ends of this segmented line were supplied with dummy F.T. messages with which to create the impression of a larger line “stretching right around the Newfoundland Banks.” That impression was not unlikely to be made, since the OIC Tracking Room was now estimating the number of U-boats at sea to be 128, the highest ever known, representing nearly 60 percent of the Atlantic operational force. When the Allies DFed the boats forming Amsel, Dönitz and Godt expected they would discover the gaps and attempt to vector convoys through them. The plan then was to combine the subgroups into a closed line. Before it had a chance to work, however, that plan was overtaken by a new plan, as BdU realized, on 4 May, that the Amsel boats would be needed in operations to the north.

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At 1602 GST (1402 GMT), Berlin began to reorganize most of the Specht and Star boats into a new reconnaissance line code-named Gruppe Fink (Finch). Ordered to be in place by 1000 GST (0800 GMT) on 5 May, the twenty-seven boats of Fink would occupy stations along a line running from west-northwest to east-southeast, or precisely, from 56°45’N, 47°12’W (AJ 2758) to 54°o9’N, 36°55’W (AK 4944)-When formed, the patrol line would stretch 382.6 nautical miles (nm), with an average spacing of 14.7 nm between the boats. As these boats were moving into position on the afternoon of 4 May, several (U—264, U—628, U—260, U-270) reported sighting destroyers (HMS Offa or HMS Oribi, or both) on southerly courses. Then U-628 (Kptlt. Heinz Hasenschar) in quadrant AJ 6271 (55°40’N, 42°40’W) at the near center of the Fink line reported at 2018 GST the mast tops of a southbound convoy that BdU had been expecting by dead reckoning, that is, by calculation based on a convoy’s course, speed, and elapsed time from a previously determined position.

This was ONS.5 (No. 33), except that BdU mistakenly called it ON.180 (convoy No. 36), which was the convoy that had been trailing ONS.5, but which on 4 May was considerably to the north tracking a WSW course through U-boat quadrants AJ 22 and 23, south of Cape Farewell. BdU was also mistaken in both its dead reckoning and real time calculations, for it expected the convoy reported by U—628 to cross the Fink recco line on 5 May, when, in fact, ONS.5 would reach the center of that line by the late afternoon of the 4th, before Fink was fully formed; and if ON.180 had continued to follow ONS.5’s course it would not have reached the line before 6 May. Apparently assuming that convoy No. 33 (ONS.5) had already passed through the Fink position, BdU’s dead reckoning error with respect to this convoy may have occurred because it was not aware that during the period 0800 GMT 1 May to 0800 4 May, ONS.5 was practically hove to in contrary weather at speeds no greater than 2.7 to 3.1 knots.

As late as 6 May, when BdU did a wash-up (postaction analysis) on this convoy (Abschlussbetrachtung Geleitz. 36), it still identified it as ON.180; but in communications to Fink boats during 5/6 May and in the war diary of 26 May it called it the “Hasenschar convoy,” after the Commander of U-628, who had been the first to sight ONS.5, at 2005 GST, and to report it, at 2018, on the 4th. The BdU practice of identifying a convoy by its shadower was common. Immediately upon Hasenchar’s report that a convoy was southwest-bound on course 200°, speed 7 knots, BdU ordered up the northernmost subgroups Amsel I and II, as well as the independently operating U-258 (Massenhausen), which had sunk McKeesport, and U-614 (Kptlt. Wolfgang Sträter), which had been temporarily hors de combat with engine problems, to join the Fink line. Twenty-seven boats strong on the night of 4 May, Fink would eventually claim a total of forty-one boats, the largest concentration ever arrayed across and around a single convoy. Dönitz and Godt reinforced this fact in a signal to the massing boats: YOU ARE BETTER PLACED THAN YOU EVER WERE BEFORE. But BdU worried that owing to fuel depletion several of the boats would not be able to operate much longer than they had.

Of these changing U-boat dispositions the OIC Submarine Tracking Room in London and thus Western Approaches had no direct knowledge until after GC&CS made a break back into naval Enigma at noon on 5 May. To that point, as Commander Winn lamented, “Nothing is known from Special Intelligence of the operations during this period.” When, however, GC&;CS could read German traffic again, the time lag between interception and decryption was so great— from seventeen hours to twelve days, the norm being four days—the information had no operational value in the battle then joined. It is possible at this date to read the GC&;CS decrypts crafted afterwards of the traffic that had passed during the blackout period. Similarly, one can consult the American decrypts of the same traffic that date from later in 1943 when U.S. Navy cryptanalysts acquired raw Enigma intercept material as well as their own “bombes” (decryption machines), hence an independent capacity to make penetrations into the German naval cipher Triton. But none of that intelligence was available at the time of battle. The principal value of Ultra in the Atlantic struggle had been its strategic disclosure of U-boat positions, and of their operational instructions from BdU. That value was lost on ONS.5. But not everything was lost. Once a close battle was joined, timely and localized intelligence such as that derived from shipborne HF/DF, radar, and asdic was far the more valuable, and that ONS.5’s escorts could collect.

By dusk on 4 May, Sherwood in HMS Tay had ample indication that he was in the neighborhood of a large U-boat formation. His FH3 HF/DF was picking up contacts on the port bow, port quarter, starboard beam, and starboard quarter. He was restricted from gaining accurate fixes, however, by the fact that communications failed between HMS Tay and FH3-equipped HMS Oribi, resulting in HMS Tay obtaining only one cross-cut fix in the next three days, 4 to 6 May. If Sherwood needed any confirmation from afar that he was surrounded, it came from the Admiralty, which signaled him at 1920 about the existence of heavy and continuous W/T traffic in his vicinity on 12215 and 10525 kilocycles. Two sweeps by the Support Group destroyers HMS Offa and HMS Oribi failed to locate any of the sending boats. The convoy was still east of 47°W and north of 4o°N, beyond which boundaries, west and south, the new Canadian North West Atlantic (CinC, CNA) Command governed all surface and air anti-submarine escorts, as decided by the Washington Convoy Conference of 1–13 March 1943. (That conference, attended by senior British, Canadian, and American naval and air representatives, also decided, among other things: that the British and Canadians would share command of the northern Atlantic convoy lanes, while the United States would concentrate her forces in the central Atlantic, including the routes of the tanker convoys between the West Indies and Britain; and that [at last] 255 VLR (Very Long Range B-24 Liberator bomber) aircraft would be delivered to the airfields on both shores of the Atlantic by July.) In the longitudes where ONS.5 sailed during the critical days of 4–6 May her escorts still remained under British operational control, although the Admiralty’s counterpart OIC in Ottawa, employing a high-power, low-frequency transmitter near Halifax, communicated HF/DF-derived U-boat position estimates to convoys, such as SC.128, eastward as far as 30"W.

Whereas SC.128 had been rerouted to evade the DFed Specht line, the suggestion has been made that ONS.5 was not similarly vectored around DFed boats before the evening of 4 May because of the escorts’ low fuel levels, and their need to continue on the shortest possible route to port. But with so many boats in movement across nearly 400 miles of ocean, there is a question if either Liverpool or Ottawa knew what possibly would have been an evasive route. The shore-based HF/DF accuracy was reported by the Admiralty to be no better than within 120 miles. Even the Admiralty message to HMS Tay at 1920 on 4 May expressed itself as being uncertain if it was ONS.5 or SC.128 that was being shadowed, so “very poor” were D/F conditions. Convoy SC.128 at the time was approximately thirty miles north of the Fink line, traversing squares AJ 28–29–34 on a course northeast by east.

Escort Group By now readied itself to run the gantlet. With 30 merchant ships present in ten columns, five cables (3,040 feet) apart, on course 202°, speed seven knots, in very clear weather, wind Force 2—a light breeze, four to six miles per hour—and a slight sea with low, long swell, Sherwood placed his night field as follows: Sunflower on the port bow, HMS Snowflake on the port beam, Tay on the port quarter, HMS Vidette on the starboard bow, HMS Loosestrife on the starboard beam, and Northern Spray on the starboard quarter—although the rescue trawler, which was astern, was delayed in taking up her station. Destroyers HMS Offa and HMS Oribi provided forward cover on the starboard and port bows, respectively, at five miles distance. Pink was leeward at 56°32’N, 40°50’W on course 235° with four stragglers, speed 5 knots; Sherwood recommended that she be separately routed, as was done. No doubt the shore commands that watched this confrontation of forces unfold, whether at Liverpool or London, Halifax or Ottawa, where enemy dispositions could only be guessed at on their wall charts and plotting tables, held their breath as the volume of HF/DF contacts mounted. At sea the incoming Morse traffic was just as ominous. Said Captain J. A. McCoy, SO, EG3 Support Group, on HMS Offa: “During all this time enemy W/T transmissions had become more and more frequent….” There was no doubt on his bridge that a multitude of foes was thickening around them.

One of the Specht boats proceeding to form Fink never made it to the party. It was taken out of the fight earlier in the day to the north-northeast of Fink, or about thirty miles astern of the convoy, by one of two Royal Canadian Air Force Canso A’s (as the Canadians called the PBY-5A amphibious Catalina flying boats) that came from Gander, Newfoundland, to give ONS.5 its first real air cover in two days, although neither aircraft met the convoy as such. The Air Gap had greatly narrowed during April and early May, with the result that on no day during its transit of the gap did ONS.5 miss contact of some kind with aircraft: even on 3 May a U.S. Army Air Force (USAAF) B-17 Flying Fortress from Gander rendezvoused with the convoy at 1538, though, at the boundary of its Prudent Level of Endurance (PLE), it could only remain with the convoy for six minutes. Nonetheless, the flyover must have caused the Specht-Star boats to keep their heads down.

At 1757 on the 4th, after a seven-and-a-half-hour flight out, the gull-gray-and-white-camouflaged Canso A “W” of 5 Bomber Reconnaissance Squadron was patrolling over position 56°35’N, 42°40’W at 2,000 feet, on course 209° True (T), with wind 20 knots from 270°T, in the base of 10/10 clouds, with visibility 5 miles in haze, when the aircraft picked up a blip on its ASV (10-centimeter) radar. The blip, which went in and out at regular intervals of a few seconds, probably as the result of high swells, indicated a target at seven miles, 25° to port. The pilot, Squadron Leader B. H. “Barry” Moffitt of Toronto, homed onto the blip and, at two and a half miles range, the second engineer, Corporal Harry Knelson of Bladworth, Saskatchewan, made a visual sighting from the port blister. The U-boat was 10° off the port bow, fully surfaced, and proceeding in a rough sea with heavy swell at a speed of 6 to 8 knots on a course estimated at 340T, or obliquely across the Canso’s own course. Its hull and tower he described as being gray in color with patches of green. Ten miles dead ahead of the U-boat, Moffitt and his second pilot could see a straggler vessel from ONS.5.

Moffitt pushed the nose down, opened the throttles, and experienced “the fastest ride I have ever had in a Canso.” Fast was a word rarely associated with the Canso. Though powered by two thunderous 14-cylinder, 1200-horsepower Pratt 8c Whitney R1830–82 engines, mounted on a 104-foot-long flexing wing, the flying boat was said by PBY pilots to “climb at ninety, cruise at ninety, and glide at ninety”— an affectionate exaggeration, since the lumbering craft regularly cruised at 110–115 knots, and could build up about 40 more knots in a power glide attack when engines were set to 43 inches manifold pressure and 2,400 rpms. As Moffitt dove out of the cloud base toward the deck, the U-boat sighted him and began an alarm dive. Leveling off at 75 feet with 150 knots indicated, Moffitt attacked from a 12:30 o’clock position, 10° off the submerging U-boat’s starboard bow, catching the target with its decks still awash.

By intervalometer, an electromechanical device that enabled a “stick” of D/Cs to be dropped at specified intervals, or spacings, he and his second pilot adjusted their four wing-mounted 250-pound torpex D/Cs, with hydrostatic fuses set to 22 feet, so that they would drop in train at spacings of 46 feet. At the optimum release point the intervalometer was activated, and the stick of D/Cs separated port and starboard from hard points on the wing, severing their arming wires in sequence: one-two-three-four. No hangups. The first D/C entered the water about 80 feet ahead and to starboard of the U-boat, the second about 40 feet from target. The third and fourth fell fewer than 12 feet off the U-boat’s port side, one forward of the conning tower, the other aft. Unaccountably, for a dive situation, two crewmen were seen on the conning tower bridge.

Moffitt kicked left rudder and pulled into a climbing turn to port. When the D/Cs detonated in train, sending gray-white water skyward in four violent geysers, Moffitt and his crew watched the U-boat heave to a fully surfaced position for about five to ten seconds, then wallow with no forward motion. After ten more seconds, the boat, still in a motionless horizontal position, sank from view. Immediately, oil appeared in bulk and grew to a slick 200 by 800 feet; four of the Canso crew members could smell its pungent odor through the open blisters. Also sighted were woodplanks with fresh breaks; these would have come from the boat’s upper surface decking, where hardwood was used to retard freezing. No survivors or bodies appeared on the frothing surface. Having reached PLE, Canso A “W” departed the scene for Gander at 1828. Back at base, Moffitt submitted photographs and guardedly reported: “U-boat probably damaged.” In London, however, the Admiralty’s U-Boat Assessment Committee decided, on 28 June 1943, that the U-boat in question, which it identified as U-630 (Oblt.z.S. Werner Winkler), was “known sunk"

Understandably, in the few accounts of ONS.5’s passage that have been written since, that has been the identification and the assessment given. In recent years, however, this and other surface and air attacks on U-boats have received a searching reassessment by Robert M. Cop-pock, Curatorial Officer, Foreign Documents Section, Naval Historical Branch, Ministry of Defence, London (hereafter NHB/MOD). Through careful examination of such factors as U-boat tracks, W/T communications, damage reports, and fuel reserves, Mr. Coppock has concluded that the boat attacked by Canso “W” was U-209 (Kptlt. Heinrich Brodda), which had sortied from Kiel, Germany, on her first war patrol on 6 April. At 1615 GST on 6 May, with her main transmitter out of commission, U-209 reported to BdU via U-954 (Kptlt. Odo Loewe) that she had suffered extensive damage: air-group no. 2 OUT OF ORDER BECAUSE OF AERIAL BOMBS. PRESSURE CONDUIT NO. I OUT OF ORDER. EXHAUST VALVES LEAKING. ONLY PARTIALLY CLEAR FOR SHOOTING. MAIN TRANSMITTER OUT OF ORDER. 29 CBM.

At 1931 GST BdU responded, ordering Brodda to refuel, if necessary, from U-119 (Kptlt. Horst-Tessen von Kameke) and afterwards to make for Brest on the Brittany coast, some 1,500 miles distant. The injured boat did not rendezvous with U-119, and nothing was heard from her again. On 23 May the BdU war diary concluded: “U-209 has been on her return passage since the 6th May. On that day U-954 reported that U-209 was damaged by aircraft bombs and unable to send signals. Fuel which were then 29 cbm must have been used up by now … so she must be considered lost.” The NHB/MOD reassessment concludes that U—209 sank by accident on or about 7 May in the general vicinity of 52°N, 38°W, and that her demise was “almost certainly” the result of the damage she suffered from Canso PBY Catalina flying boat “W” on 4 May. Winkler’s U-630 will be seen later in the narrative.

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Another type of engagement was experienced by the second Canso that approached ONS.5 that afternoon. Piloted by Flight Lieutenant J. W. C. “Jack” Langmuir of Toronto, Canso A “E” of 5 Squadron sighted 15 to 18 miles ahead a fully surfaced U-boat proceeding at about 8 knots on a course of 132°T. He later estimated its position as 55°35’N, 43°14’W. The Canso’s course was 023° at 5,500 feet. The time was 2045. Langmuir turned on a reciprocal course to the U-boat in order to get the sun at his back, and then, at 8 miles distance, he commenced a dive, going to 20 feet off the deck at 155 knots, and aiming almost directly at the U-boat’s bow, hoping for a perfect straddle. During his run in, the “dark brown-green” U-boat, deciding to fight it out on the surface rather than dive, opened up with 20mm anti-aircraft fire from the flak platform aft the conning tower. Pressing on, Langmuir hit the release button and got his perfect straddle, numbers 2 and 3 of the stick entering the water not more than 15 feet to either side of the U-boat’s hull, between the conning tower and stern.

As the Canso banked away to port, her crew observed the U-boat’s bow lifted above the surface by the explosions, showing daylight between the keel and water for about one-third of the boat’s length; yet the boat was still able to maneuver, and did so, making a complete 360° turn to starboard while “pitching and rolling violently” and persisting to offer flak. With all his D/Cs expended, Langmuir moved out of range and ordered the bow gunner, Warrant Officer Clifford Hazlett of Chilliwack, British Columbia, to mount a. 30-caliber Browning machine gun in the bow turret, which took about three minutes. Langmuir then made a second run at the boat. Descending from 200 to 50 feet, he called for fire from both the bow gun and the. 50-caliber gun in the starboard blister, beginning at 400 yards. Two U-boat crewmen on the flak platform were seen to fall, hit, and to crumble over railings into the sea.

After the pass, Langmuir banked to starboard intending to make a third run, but when he looked back he saw only the U-boat’s bow as the craft submerged at an awkward angle. No oil, debris, or survivors were sighted. Having done as much as she could do, Canso A “E” began the long return to base. A large number of photographic negatives were presented at Gander as witness to the action. The assessment from London on 28 June was, “Probably slightly damaged”—a tribute to the integrity of the U-boat’s hull, which took at least two D/C charges within close range. The U-boat was identified later from Enigma intercepts as U-438 (Kptlt. Heinrich Heinsohn), out of Brest, which signaled to BdU at 0608 on 5 May that she had had an exchange of fire with an aircraft and received minor damage: 4 BOMBS FROM CATALINA 15 METERS OFF.… ATTACKED SEVERAL TIMES BY FLYING BOAT. NO. 40 CYLINDER COVER TORN. OTHER DAMAGES SLIGHT. Later that day she reassured BdU: CAN REPAIR DAMAGES TO ENGINE WITH MEANS ON BOARD.

On the cusp of battle, as a five-hour night fell across the bleak dress of the North Atlantic, Admiral Dönitz’s U-Boat Command had every reason to be confident. The initial conditions for a convoy fight had never been so favorable. Forty-one boats were forming the battle line, and a convoy had steamed into their near-middle. At 2213 GST (2013 GMT) Dönitz signaled one last personal exhortation to his commanders:

I AM CERTAIN THAT YOU WILL FIGHT WITH EVERYTHING YOU’VE GOT. DON’T OVERESTIMATE YOUR OPPONENT, BUT STRIKE HIM DEAD!

First out of the box was twenty-eight-year-old Kptlt. Ulrich Folk-ers, commander of the Type IXC U-125, which sortied on 13 April from her home base with 10th Flotilla at Lorient, a name that soon was to have a curious reprise. On his first patrol Folkers had sailed to the U.S. East Coast in January 1942 as a member of Operation Drumbeat (Paukenschlag), during which he sank only one vessel, the 5,666-GRT American freighter West Ivis. In three subsequent patrols, however, he put fourteen Allied ships in the locker and received the Knight’s Cross in March 1943. His actions on the night of 4/5 May are not known with any accuracy because neither his war diary (KTB) nor his torpedo shooting reports (Schussmeldungen) survived the battle. But German message traffic gives him the first trophy of the night, merchantman No. 34 in column No. 3. Her name: Lorient. Built in 1921 by Tyne I.S.B. Co. Ltd., Newcastle, the 4,737-GRT Lorient was transporting trade for the Continental Coal and Investments Company of Cardiff. Captain Walter John Manley commanded her merchant crew of forty-six officers and men. On the night of 4 May, without notice or trace, she simply disappeared, with all hands.

Convoy rules specified that upon being torpedoed, a ship should send up two white rockets and key the emergency signal SSS (Struck By Torpedo) on the 600-meter distress band. Lorient did neither. Unless she was broken in half, a torpedoed ship in ballast, as Lorient was, normally should have had enough buoyancy to stay afloat long enough to make a signal, as well as get her crew away in boats. However, as the next ship to go down demonstrates, that amount of time could be as little as two minutes. In any event, no crewman or debris from Lorient was ever found. Commodore Brook commented simply that Lorient “parted company,” probably indicating no more than that she had become an out-of-sight straggler. The conclusion that Lorient’s end came at the hands of U-125 is based on a signal from Folkers to BdU, repeated by the latter to all northwest Atlantic boats at 0218 on the 5th: FOLKERS REPORTS ON 36 METERS. ON 4 MAY IN QU AJ 6298 [55°33‘n, 41°45’W] INDEPENDENT 4000 TONNER, COURSE 220, SUNK.30 Lorient would be U-125’s only victim in the battle. Fewer than thirty hours later, U-125 would be a victim herself.

Significantly, at this same early hour of the battle, Kptlt. Helmuth Pich, Commander of U-168, reported that he was breaking off the line because of fuel shortage. Just as significantly, BdU, which had fretted over the fuel problem from the time Fink was organized, signaled back that it would not permit it. Pich was to continue operations, and all boats were to remain engaged until their fuel state reached five tons, when they could disengage to resupply from a Milchkuh standing well clear to the east. Pich was back in the line at 2246.31 The second U-boat to take offensive action was U-707, a Type VIIC commanded by Oblt.z.S. Günter Gretschel. At 2153 Gretschel dived ahead of the convoy, intending to attack at dusk:

[Through the periscope] “I can see two destroyers [Offa and Oribi?] zigzagging regularly ahead of the convoy. Asdic is being used only in short spurts. One destroyer is now only 1000 meters distant, dead ahead … ; now it zigzags toward port again. Nothing can be seen of the convoy. I think that all’s clear and that I’m through [the screen] when a destroyer heads right for me again. He must have located me [by asdic] because I’m proceeding at a very low speed. Now his asdic is continuous. I dive deeper to A 20 [a prescribed but varying depth such as 30 meters plus 20 meters]. Eight well-placed D/Cs [Wabos], The convoy passes overhead.”

The D/C attack was made by HMS Tay, which had moved to close ahead of convoy.33 Gretschel continued:

“Surfaced. I am in the rear of the convoy formation. To the front are a few shadows, to starboard a corvette, astern, a large steamer. Battle stations! [Auf Gefechtsstationen!] I attack a modern passenger steamer of the type City of Manchester, with protruding bow and continuous deck, 7500 GRT, on course 210°. I launch a fan shot from Tubes I, II, and IV, bearing 90°, range 1500 meters. After a run of one minute, 34 seconds, an eel hits abaft the mast, causing a high black detonation column. Immediately, the steamer begins sinking by the stern. The upper deck is awash. The vessel remains floating for awhile, then suddenly stands itself up, the bow vertical, and descends into the sea. Time for sinking: 69 seconds. Secure from Battle Stations! Dive to reload.”

This time the sinking was observed by the armed trawler H.M.T. Northern Spray, commanded by Lieutenant F. A. J. Downer, R.N.R. The victim was not the type of passenger steamer Gretschel identified, but a 4,635-GRT freighter of the North Shipping Company in Newcastle. Named North Britain, she had straggled from the convoy in bad weather on Saturday, 1 May, had rejoined on the 4th, but then had straggled six miles astern again with boiler trouble. The record does not state how many of Gretschel’s torpedoes hit home, but is clear that his victim, which was in ballast, sank very quickly, stern first, inside two minutes. The time was 0027 on 5 May. Northern Spray, which was nearby, carried out an “Observant” around the spot of sinking but failed to make asdic contact. No boats or life jacket lights could be seen, and the trawler reported to Tay that there were no survivors of the crew of over forty. Then, at 0055, some lights were sighted, and ten minutes later the trawler discovered a waterlogged lifeboat and a raft. Repeatedly the lifeboat was brought alongside, but the ten exhausted crewmen inside it made only lethargic efforts to get out. Finally, they and an eleventh survivor on the raft were taken on board, and Northern Spray proceeded to the positions of other sinkings.

Hasenschar, the contact-keeper in U—628, was next to open a fighting account. With seven other boats of his knowledge in contact with the convoy by dusk (U-707, U-202, U-264, U-265, U-168, U-732, and U-378), he thought himself free to shed his shadower’s role—Somit ist für mich Angriff freigegeben:

“I move toward the convoy columns [on the surface] so I can attack just at the beginning of night. The sea state is 3–4, moderating with a light swell. Visibility is good. As it gets darker the starboard bow escort steams far off to the west and a second destroyer heads south. I’m successful in getting through the hole between them, and now, at first darkness, I’m in contact with the main body of the convoy. Positioned west of the convoy, I start my attack.… I don’t think it’s advisable to proceed any closer because escorts on the beam can approach me at short range. In spite of the great distance to target I decide to launch exactly aimed individual shots, because I have precisely calculated target data. All Etos are hot and ready.… At 0043–0046 I launch from Tubes I through IV at five [sic] different freighters in a row, range 4000 to 5000 meters, torpedo depth set to three meters.… Then I turn to starboard and make a [single] stern launch, after which I take off on the surface, full speed, toward the northeast because the starboard escorts have moved in my direction again. Calculating from the time of the first torpedo launch, there were four hits, the first after a run of 7 minutes, 58 seconds, the last after 9 minutes, 30 seconds. There was a 3-minute interval between the launch from [bow] Tube I and the launch from [stern] Tube V. We could only observe three hits. The first, which had a high detonation column, was on a large freighter. The others were on two medium-sized freighters. One explosion was very large, so one could assume a sinking. The third freighter hit shoots two white rockets and begins to burn. As we back off from the scene, a muffled explosion is heard at 0105 from the first, large freighter, possibly a boiler explosion. A large black cloud of smoke hangs over the ship for a long time. Then there is nothing more that can be seen of the ship. In the boat we can hear the noises of a sinking ship. The ship sinks. As we continue our withdrawal the rear echelons of the convoy send up illumination flares continuously. Some of the flares are very close, but we are not spotted.… Because I have one eel left I decide to return to the scene in order to sink a ship that might be damaged.… At 0225 I observe a shadow with a weak red masthead light. At first it shows little aim-off bearing. For a short while I pursue it with diesels at slow ahead. Now we recognize it to be a corvette, hove-to, bearing 110°. I approach to a range of 800 meters and at 0302 launch a single eel, set at 4 meters depth, from Tube III. After 28 seconds running time there is a huge tongue of flame, followed by spark showers, then nothing more to be seen. A strong shockwave followed. I guess that the entire D/C stowage exploded. The corvette had literally gone up in thin air.”

Later, in reporting these attacks to BdU, Hasenschar stated that he had sunk one large freighter, probably had sunk a medium-size freighter, had left a third freighter burning, and had blown a corvette to pieces—”Atomisiert.” But the twenty-six-year-old Commander was peering through rose-colored binoculars. Only one ship was hit by his torpedo barrage: the 5,081-GRT freighter Harbury, with a cargo of 6,820 tons of anthracite coal. As for the vaporized corvette, HMS Snowflake, HMS Sunflower, and HMS Loosestrife—Pink was on another course—continued rolling and pitching on their assigned stations, unscathed by anything but weather. Some of the explosions reported by Hasenschar may have originated with torpedo hits scored in the same time period by U—264 (see below). Or they may have been end-of-run detonations.

With a loud explosion, but no flash, one of Hasenschar’s wakeless torpedoes struck Harbury on the starboard side in No. 5 hold, blowing off its hatches and flooding it. The time was 0046 on 5 May. A fracture in the tunnel door allowed water into the engine room, which began to fill with sea water. The Master, Captain W. E. Cook, made his way to the bridge wings, where he saw that the ship was settling by the stern. Third Officer W. Skinner fired the required white rockets. Only twenty-one or twenty-two years old, Skinner had previously gone down once with a mined ship, a second time with a ship sunk by Japanese aircraft off Ceylon, and, after the latter sinking, he had been sunk yet a third time by a Japanese cruiser that shelled the ship that rescued him. Said Cook later about Skinner’s fourth experience, he was “most reliable and cool.”

As the well deck went under water, Cook switched on the red lights to mark his position, stopped engines, threw overside the weighted Confidential Books, directed a distress W/T message to be transmitted, placed a W/T set in one of the main lifeboats, and ordered Abandon Ship. The crew succeeded in lowering the two main lifeboats amidships, but the starboard quarter small lifeboat had been rendered useless by the explosion, and the port quarter boat capsized on becoming waterborne. Several lives were lost when a knot of crewmen stranded aft were forced to jump into the sea. Cook remained on board with two crewmen and searched the ‘midship accommodation to make sure that all fifty-one crewmen, including seven Navy and two Army gunners, had gotten off. Near midnight the ship gave a “grinding and wrenching” sound from aft, leading Cook and the two ratings to think that Harbury was sinking. They hurriedly boarded the forward starboard raft, cast off the painter, and drifted away into a heavy swell and dark night. In the distance they sighted two white lights, which they assumed belonged to the lifeboats.

Around 0320 they observed a shower of sparks and heard a loud explosion, which they interpreted to be an end-of-run torpedo detonation, and an hour and ten minutes later they sighted Northern Spray. Cook attracted the trawler’s attention using a newly issued handheld rocket that threw up five flares. With some difficulty because of the rough sea and the lack of ring bolts or cleats on merchant ship rafts to which lines might have been made fast, the trawler hauled on board the raft’s occupants and, a short time later, those also from the lifeboats, making a total of forty-four men rescued, six of whom were slightly injured. Seven were missing.

In the morning (0900), Cook, with his Chief Officer and the First Lieutenant of the trawler, took a boat to inspect Harbury and to secure flour and potatoes from her pantry to replenish the trawler’s dwindling stock. They found water ten feet high in the engine room, above the dynamos, and saw that the sea was pouring into No. 4 main hold. All indications were that Harbury would sink. At 1000 the boat party returned to Northern Spray. A month and a half later, Cook would say: “I did not see my ship again, but in view of her condition I am certain that she eventually sank. Aircraft were sent out the following day to the scene [55°oi’N, 42°59‘W] but no sign of the ship could be found.”

Hasenschar’s KTB, which has not always been reliable, proved to be correct about the fate of the Harbury wreck. At 1230 on the afternoon of 5 May, while proceeding underwater near the position 55°14’N, 43°02W, Hasenschar sighted a stopped, presumably damaged, freighter in his periscope lens. He surfaced, decks awash, long enough to make an observation from the bridge, then submerged again:

“I approach the freighter with full speed underwater. With the periscope I can see that the steamer has been abandoned. It has a slight list to starboard and it’s down by the stern. Lifeboats hang out of their davit arms. Stairs and lines hang outboard. At 14511 surface and clear the guns at a distance of 300–400 meters. With 40 rounds of 8.8 fire from the forward deck gun and 100 2cm armor-piercing shells we get the freighter to sink.… It lists to starboard and then capsizes.… The vessel displays a repainted shipping company insignia of the “Harrison Line” on the funnel. A drifting cutter with sail nearby carries the name “Harbury”. The freighter fits the silhouette of that type. I assume that this is the damaged ship that we torpedoed the night before.”

He was right. S.S. Harbury was owned by J. & C. Harrison Ltd., of Mark Lane, London. Hasenschar also identified this derelict as Harbury in his Schussmeldungen, unfortunately the only shooting reports to survive in German archives from any U-boat operating in May 1943. The young U-Boat Commander would go down with his boat on 3 July 1943 northwest of Cape Ortegal, Spain.

Hard on the heels of Harbury s torpedo, two more ships took hits, the work of Kptlt. Hartwig Looks in U—264. At 0014, Looks placed his Type VIIC boat ahead of the convoy, on the surface, with the intention of attacking inside the port bow and port beam escorts (Sunflower and Snowflake). A “destroyer” (Tay) visible to the north did not see him in the overcast weather, visibility good but very dark, rough sea with heavy swell, wind from the southwest Force 5. At 0100,14 minutes after Harbury was struck, Looks made his move:

“I have a group of five steamers ahead of me, three at approximately 1500 meters and two behind them at about 2500 meters.… At 0102 I launch two fan shots at the larger two of the three nearest ships, one launch of two eels from Tubes II and III at a 6000-tonner and another launch of two from Tubes II and IV at a 5000-tonner. Range 1500 meters, angle on the bow 3.8° and 3.9°, respectively. Torpedo depth set to 3 meters. I then turn hard-a-starboard and launch a fifth eel from the stern tube at a 4500 GRT freighter. All five eels hit home. The first fan launch at the 6000-tonner detonates after runs of one minute, 22 seconds and one minute, 26 seconds, one hitting amidships and the other 20 meters from the stern. Two high smoke columns can be seen. The second fan launch hits the 5000-tonner at the same locations on the hull after runs of one minute, 47 seconds and one minute, 51 seconds. Again there are two high detonation columns. The single launch from Tube V hit the 4500-tonner amidships under the funnel. There is a very high detonation column topped by a large mushroom cloud. I suspect that all three steamers will sink because of the good positioning of the hits. I take off as fast as I can. A destroyer heads toward me from the north at high speed. The steamers I hit shoot up white rockets.”

Looks’s observations were in the main correct. The larger two steamers were each hit by two torpedoes. But the stern launch at the “4500-tonner” missed, and since no other ship in the convoy was struck within the previous 19 minutes or during the one hour and 17 minutes that followed, there is no accounting for the third explosive scene described by Looks and reported by him to BdU at 0234. The first vessel hit was West Maximus, a 5,561-GRT American Hog Islander general cargo vessel in ballast, with 745 tons of slag, ship No. 22 in column 2 on the port side of the convoy. Twenty-five seconds later, a British freighter, the 4,586-GRT Harperley, No. 13 on the outside port column I, took the first of two torpedoes that would puncture her hull.

Neither of the two merchant seamen lookouts on the bridge nor any of the nineteen U.S. Navy gunners at their stations, sighted a wake from the first torpedo absorbed by West Maximus The explosion, which caused the entire ship to shudder, blew open the port side in the after peak tank and took away part of the stern section. The second torpedo, entering No. 3 hold on the port side, demolished No. 3 aft bulkhead, flooded the fire room, showered the vessel with fuel oil, and buckled the deck plates so badly, said the Naval Armed Guard commander, Lieutenant (jg) J. C. Dea, U.S.N.R., that “it was virtually impossible to walk on the deck.” The Master, Captain Earl E. Brooks, immediately ordered Abandon Ship. Of the sixty men on board—thirty-nine merchant crew, nineteen gunners, and two U.S. Army passengers—all but four made it safely down the nets and ladders into four lifeboats, from which, eventually, they were delivered by Northern Spray. The freighter went down by the bow at 0135, taking with her the Confidential Books, which Captain Brooks had, for one reason or another, neglected to deep-six. Neither had he gotten off a W/T distress signal nor fired white rockets—though, in Lt. Dea’s opinion, “torpedoed ships should not throw out white flares, as they illuminate the area and create visible targets.”

On Harperly, a sister ship to Harbury, the Master, Captain J. E. Turgoose, who was seventeen days into his first command, saw the flashes of the torpedoes that struck West Maximus to starboard and slightly ahead in the adjoining column. Moments later, his own vessel was jarred by two torpedoes that exploded through the half-inch-thick hull almost simultaneously, one entering the vicinity of the engine room, the other in the way of the foremast. Turgoose, who was in the wheelhouse at the time, was surprised that the explosions were muffled—more like dull thuds, he said later—and that there were neither detonation flashes nor columns of water that he could see, though survivors from another ship told him afterwards that they saw the flashes. Equally surprising to Turgoose was the fact that at first there was little visible damage—the windows of the wheelhouse were unshattered, for example—but reports came into him thereafter that Harperly was listing heavily to port, and for that reason she was hiding broad sea-sucking holes in the ship’s side.

Turgoose had the rockets fired—one failed to function—and had an SSS transmitted. The engine room telegraph was jammed, but the engines had already been stopped by the first torpedo, which also took the lives of the Second, Third, and Fourth Engineers. The Second Engineer, W. J. Gilbert, had only moments before volunteered to give up his off-watch time to help with the engines. With the ship’s list increasing, Turgoose ordered Abandon Ship. One of the port lifeboats had been destroyed, but the crew successfully launched three serviceable boats and made clear of the ship within the space of eight minutes, Turgoose having to jump to join one of the boats. Ten to fifteen minutes later, he watched his ship disappear by the head. Two men were heard “moaning and shouting” in the water, and by hard pulling on the oars, Turgoose’s boat managed to rescue one of them. Two other men clinging to the bottom of a small lifeboat that had capsized went under before they could be reached.

After three and a half hours Northern Spray answered the emergency W/T and lights. Thirty-eight survivors were lifted on board the trawler to join fifty-one from West Maximus, forty-three from Harbury, and two from North Britain. Lt. Downer wondered where he would put them if he had to pick up any more. Every open space on his small 150-foot vessel, including the mess decks, ward room, and cabins, was jammed with damp bodies, panic bags, and (from West Maximus) American luggage. The trawler’s cook, Herbert Arthur Damsell, contrived somehow to serve up meals for everyone, using, among other provisions, the providently salvaged flour and potatoes from Harbury. Damsell refused the help offered by cooks from the other ships, saying, “I don’t want any strangers in my galley.” Northern Spray was ordered by Sherwood to St. John’s, which was reached without incident at 0750 on the 8th. Any further survivors would have to be rescued by B7’s warships.

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6 THE FOG OF WAR

The Battle for ONS.5

It was the job of the little ships and lonely aircraft, a hard, long and patient job, dreary and unpublicized, against two cunning enemies—the U-boat and the cruel sea.CAPTAIN GILBERT ROBERTS, C.B.E., R.N.

A war of groping and drowning, of ambuscade and stratagem, of Science and Seamanship.WINSTON S. CHURCHILL

BOTH BEFORE AND DURING the two and three-quarter hours when five ships of Convoy ONS.5 went to the seabed, Lt.-Cmdr. Sherwood and his escorts were urgently hunting their German adversaries, in line with a principle contained in the Tactical Policy issued by Admiral Horton on 27 April, viz., that U-boats were most successfully detected and destroyed prior to their attacks. Fittingly, it was HMS Tay that was first to take the fight to Fink. At 2247,3 in her night station on the port quarter, Tay obtained an asdic contact at 400 yards. She promptly attacked with a ten-pattern. There was no visible result, and Sherwood judged that his contact was not a submarine, since there were “many Non-Sub echoes” in the vicinity. The NHB/MOD reassessment, however, concluded that there had been a submarine present, and identified it as U-707 (Gretschel), which was not damaged.

Second to make an attack that night was Lt. Raymond Hart in HMS Vidette. The thirty-year-old destroyer captain had joined the Royal Naval Reserve in 1931 after two years with the Royal Mail Steam Packet Company, and served six months on the battle cruiser HMS Hood. When his merchant navy junior officer’s position fell victim to Depression-era cutbacks in 1934, he moved to Canada, where he took up lumbering. In 1937 he returned to the sea as a probationary sublieutenant in the RN, and when war broke out he was serving on the destroyer HMS. Hasty, on which he later took part in the battles of Calabria and Cape Matapan and won the D.S.C. in an action off Tobruk. During Operation Vigorous to revictual Malta in June 1942, HMS Hasty was damaged by a German torpedo boat (S-boat) and had to be sunk by another destroyer. From June to October of that year Hart commanded a demolition team called the Hornblowers whose job it was to destroy stores and disable the port facilities at Alexandria should that base be threatened by German occupation. In December 1942, he was given his first sea command in the elderly HMS Vidette and assigned to B7. Gifted with intelligence, judgment, and sound seamanship, he has been described as “good-looking” and “dashing.”

At 0020 on 5 May, HMS Vidette was stationed in position “D,” 6o° and 5,000 yards on the starboard bow of ONS.5, when her Type 271 radar set picked up a pulse echo bearing 205°, 3,600 yards. Increasing speed to 22 knots, Hart sighted the U-boat five minutes later. At 700 yards the U-boat dived, and at 0030 HMS Vidette’s D/C team fired and dropped a fourteen-charge pattern at shallow, or ramming, settings over its swirl. The attack damaged the Type IXC U-514, whose Commander, Kptlt. Hans-Jürgen Auffermann, reported to BdU that the charges put his fixed periscope out of order and placed the flange of his starboard stern tube beyond repair; not until the early hours of the 7th, when the battle for ONS.5 was over, would he report that he was capable of further operations.

After opening range to 2,000 yards, Hart returned at a new angle to the attack position hoping to get asdic response, but there was none, and he commenced an operation “Observant.” During the second leg of that maneuver, at 0050, another radar contact was acquired bearing 285°, 3,600 yards, and HMS Vidette chased up the new bearing, sighting a U-boat known today to have been U-662 (Kptlt. Heinrich Müller), range 1,000 yards. Electing to attempt an attack before the enemy had a chance to dive, Hart ordered full ahead both engines and Stand By to Ram. The 20mm Oerlikon gunss opened fire, but while their tracers illuminated the U-boat’s conning tower, they also temporarily blinded the destroyer’s bridge personnel. Oddly, the U-boat appeared to be “reluctant to dive"; that may well have been because U-662 at that same time was attempting a stern attack on HMS Vidette. Finally, she did flood tanks and dive. HMS Vidette was able to approach to within 80 yards before the conning tower fully submerged, but not in time to ram. The destroyer proceeded through the swirl and, at 0059½, fired a fourteen-charge pattern in what Hart thought was “an accurate attack.”

Though it was not, it turned out, as accurate as he thought, it had the serendipitous effect of rattling a nearby boat, U-732 (Oblt.z.S. Klaus-Peter Carlsen), which recorded being depth-charged at the same time. Already nursing earlier injuries, U-732 was forced by the Wabos to move off for Rückmarsch (return voyage) to Brest. Following his procedure in the previous attack, Hart opened the range, this time to 1,700 yards, and returned seeking asdic contact; again there was none, and again he commenced “Observant.” At 0125, however, the asdic recorder traced the presence of a U-boat in almost the same position of the last attack, and at 012½= Hart fired twelve charges (two more intended D/Cs not being set in time). No visible signs of success followed, and at 0150 Sherwood ordered HMS Vidette to resume her station (Offa had been covering).

Hart’s aggressive spirit was matched by that of Lt. Chesterman on HMS Snowflake. When convoy ships Harbury, West Maximus, and Harperley were torpedoed within nineteen minutes of one another (0046–0105), Sherwood ordered operation “Half-Raspberry.” In a full Raspberry maneuver, all close escorts initiated triangular searches employing starshell illumination rockets. The various triangular patterns to be followed as well as the individual escort sweep speeds and time durations were carefully spelled out in the Atlantic Convoy Instructions. In a “Half-Raspberry” the Senior Officer could modify the maneuver, for example by holding some escorts in place. We know from HMS Snowflake’s report that at 0055 she participated in the Half-Raspberry by turning hard-a-starboard to course 335° and proceeding to carry out a 12-knot triangular starshell sweep at the port quarter of the convoy.

At 0104 she fired starshell illuminating an arc 030° to 150°, and at 0108, following the maneuver diagram, she altered course to 210°. One minute later, she received a radar blip bearing 255°, range 3,000 yards, which she pursued at full speed, soon sighting a U-boat on the surface by light of the starshell. At 0111 the corvette’s hydrophone picked up the sound (compressed air release) of a torpedo being launched at close range. HMS Snowflake continued the chase, but there was little chance of catching up since the Flower’s top speed of 16 knots was below that of the U-boats’ top surface speeds of 17 (Type VIIC) and 181/4 (Types IXB and IXC) knots. Accordingly, when HMS Snowflake picked up an asdic bearing of 170°, range 300 yards, indicating a possible submerged U-boat, Chesterman elected to attack that target instead, firing a ten-charge pattern of light D/Cs set to 50 feet and heavy D/Cs set to 140 feet. Fired by stopwatch at 0116, the attack produced no evidence of a hit (it is now concluded by the NHB/MOD reassessment that no submarine was present), and the blast effect of the charges set shallow had the unfortunate effect of fracturing the leads to HMS Snowflake’s asdic motor alternators and blowing the bridge fuses.

Instead of returning to the swirl position, Chesterman renewed his pursuit of the surfaced U-boat he had sighted earlier, harrying it with starshell and four-inch gunfire. Finally, he was relieved to see it dive and thus place itself for the time being out of the game. Passing over the swirl at 0127 Chesterman dropped five light charges set to 100 feet. A minute and a half later, his lookouts sighted a torpedo passing 150 yards ahead from port to starboard. Even though he had forced a dive, Chesterman was not pleased with the surface chase sequence. “Consider I was bluffed by the U-boat into wasting charges,” he entered on his report. The boat has been identified by the NHB/MOD reassessment as U—264 (Looks), which was not harmed.

After having resumed station on the port beam, course 260°, HMS Snowflake received a radar return bearing 175°, 3,400 yards, and so informed HMS Tay at 0322. The corvette pursued the bearing and when range closed to 2,000 yards she gained the hydrophone effect of highspeed diesels. Chesterman needed faster horses. “Chasing U-boat, unable to overtake,” he called to HMS Tay by TBS (Talk Between Ships) radio telephone (R/T) at 0339. Sherwood passed the word to Support Group senior officer McCoy, in HMS Offa, which resulted in the following exchanges:

OFFA TO ORIBI [0341]: If in vicinity assist Snowflake to chase U-boat.

SNOWFLAKE TO ORIBI [0345]: My position one-two-zero-Z-Z-nine.Are you joining me?

ORIBI TO SNOWFLAKE [0351]: Am proceeding to help you.

SNOWFLAKE TO Oribi [0352: Course one-seven-zero. U-boat half-a-mile ahead of me.

At this point HMS Snowflake found that she was gaining on the U-boat, which apparently was not proceeding at highest speed, and at 0358 she opened up with starshell, four-inch projectiles, and Oerlikon fire. HMS Oribi came up from astern, also firing starshell. At 0359 Chesterman called: “U-boat dived, dropping charges.” With “firm contact” by asdic, at 0400 Chesterman fired five light charges set to 100 feet. He maintained asdic contact until 0414, when he dropped four heavy charges set to 225 feet, after which, anxious about running short of D/Cs, he asked HMS Oribi’s captain, Lt.-Cmdr. J. P. A. Ingram, to take over the attack. HMS Oribi, which earlier, at 0247, had dropped two single D/Cs on what turned out to be a false radar contact, attacked the asdic position held by HMS Snowflake with two ten-charge patterns, at 0445 and 0508. The two attacks were handicapped by defective gyro compass repeaters, and at 0417 Oribi had had to ask HMS Snowflake to be the directing ship, passing ranges and bearings, which she did until 0520, when Chesterman laid course to rejoin the convoy. HMS Oribi also abandoned the search at 0554 on orders from HMS Offa, without having seen any evidence that would enable him to know that his first ten-pattern had caused heavy damage to the Type VIIC U-270 (Obit. z.S. Paul Otto).

In his KTB, Otto described how the first barrage sent his boat plunging toward the bottom with a forward list of 20°: “The depth-pressure gauge is maxed out.” By running the E-motors at full emergency reverse (A.K.-zurück) he managed to slow the descent, and by pumping all available trim water to the stern tanks as well as by sending every crewman climbing into the aft torpedo room he got the boat righted, and was able to begin blowing the ballast tanks to reach a safe depth. As the boat rose, it remained bow-heavy from sea water that was pouring through fractures in the hull forward at a rate of one to two tons per hour. Finally, at 1024 GST, Otto was able to surface. After studying the damage reports, he listed seven categories of Ausfälle (breakdowns) in his KTB. There was no alternative but Ruckmarsch.

Unfortunately for ONS.5, her few defenders could not keep the entire German host submerged and thus for the most part, neutralized. At 0144, Kptlt. Rolf Manke in U—358 could see several steamers from the bridge of his conning tower. They were on course 200°, passing through the position of a sinking, where, Manke noted, “at least ten lifeboats with lights were floating about.” (West Maximus and Harperley had been torpedoed 42 and 39 minutes before.) “The first of the steamers stopped to take on board the occupants of one of the lifeboats.” Manke chose that one for a fan shot from Tubes II and III. The Pi 2 pistols that would detonate the Torpex warheads of the torpedoes were adjusted to accommodate the high swells, and the torpedoes’ depth mechanisms were set to run at four meters.The target ship lay hove-to at a range of 1,500 meters. That number, together with the target’s speed, o knots, and bearing, Red [port] 8o°, was fed into the electromechanical deflection calculator (Vorhaltrechner), and the trigonometric solution of the aiming triangle (a simple calculation, since the target was stationary) was transmitted by it to the torpedo launch receiver (Torpedoschussempfänger) in the forward torpedo room, which in turn fed the heading into the guidance systems of torpedoes II and III. When the Petty Officer (Bootsmaat) at the torpedo station acknowledged completion of the process by the word Following! (Folgen!), Manke’s first watch officer (I.W.O.) gave the launch order at 0222: “Launch fan shot!” (“Fächer los!”)

Manke described the result in his KTB:

“Two explosions were heard in the boat after the 113 seconds run, so perhaps both torpedoes hit. A violent explosion could be seen midships. The steamer broke apart in the middle and sank within one minute. Because of the vessel’s length (150 meters) and its 5½ hatches, I judge the steamer to be 8000 GRT. According to Gröner [merchant ship silhouette identification handbook] she belongs to the Port Hardy class (8700 GRT).At 0248 Manke ordered the launch of a single eel against the next freighter in line, range 1,600:Launch order given. But the torpedo stuck in the tube. A Mechanikersmaat [Machinist’s Mate] prodded it out with a mine ejector and it hit the target after a run of 118 seconds. A large explosion resulted amidships on the target and the steamer broke apart and sank in a matter of seconds. From Gröner we judged the vessel to be of the Clan Macnab class, 6000 GRT.… Only a destroyer and another escort could now be seen. We pursued the convoy, whose position was obvious from the frequent shooting of flares, but then, because of the sea force and swell, we dived in order to reload in a stable environment.”

Manke hit his ships all right, but their tonnages and fates were not as described in the rather inflated account he leaves us, for neither sank “within one minute” (versank innerhalb einer Minute) or “in a matter of seconds” (versank in wenigen Sekunden). The first vessel hit was the freighter Bristol City, bound for New York with a 2,500-ton cargo of China clay (also called kaolin, used in the manufacture of china or porcelain) and general goods. Her GRT of 2,864 tons hardly measured up to Manke’s estimate of 8,000. And in her stricken condition she survived well beyond a minute.

At the time of U-358’s first torpedo, Bristol City was in position 54°oo’N, 43°55’W (AJ 6517), heading column No. 1 on the extreme port bow of ONS.5, steering a course of 197° through a sea with heavily confused swell; a southwest wind was blowing Force 5; and the overcast night was very dark, though with good visibility. No one on board sighted the torpedo before it exploded in No. 4 hold on the freighter’s port side. Her Master, Captain A. L. Webb, who was on the bridge, stated later that: “The explosion was dull, much quieter than I would have expected. I saw a flash, and a huge column of water was thrown into the air, which cascaded down and flooded the decks.” One immediate result of the blast was the collapse of the main topmast and the blowing off of hatches and beams. So much debris fell on the deck that it was difficult for Webb to assess the exterior damage, although he specifically observed that the port lifeboat and after rafts were wrecked. More serious was the flooding below of No. 4 hold and the engine room. Webb rang for the engines to be stopped.

“A few minutes later,” he remembered, a second torpedo struck his ship, with no flash, in No. 1 hold. But he also miscalculated times. The interval between torpedoes II and III of Manke’s fan shot should have been no more than seconds. A Facherschuss, such as Manke employed, was a simultaneous spread of two or more torpedoes; it differed from a Mehrfach, which was a multiple, though not simultaneous, launch. In any event, the second eel compounded the damage to Bristol City, collapsing the fore topmast, destroying the windlass, blowing off one of the forward rafts and hatches from Nos. 1 and 2 holds, and flinging China clay into the air. Webb was unable to get rockets off, but M.V. Dolius in the adjoining column to starboard sent up two. Nor was Webb able to get an SSS off, since the wireless room had been wrecked. He did see to it that the Confidential Books, which included the Wireless Codes, were secured overboard in weighted boxes. Then, recognizing that there was no hope for Bristol City, he ordered Abandon Ship.

Twenty of his crew of forty-four, which included four Navy and two Army gunners who never saw their assailant, jumped from the main deck into the sea to join the starboard lifeboat. A jolly boat with five occupants capsized on reaching the water, casting the crewmen overside; three of them were lifted into the lifeboat, while two floated off and were not seen again, despite the fact that all the crew wore life jackets with red lights. Webb was the last to leave the ship, which was not broken in two, as Manke observed, but had settled by the head and was steaming under; the Master was waist-deep in water before he swam off into the swells, where the lifeboat found him. When the ship finally disappeared it was nine minutes (not one) after the first torpedo had struck. A little more than an hour later, the survivors, three of them injured, were rescued by the corvette HMS Loosestrife. Fifteen of the crew were missing, presumed killed by the torpedoes, or drowned, or carried off in the swells.

The second ship, which was hit by Manke’s single torpedo launch, was S.S. Wentworth, a 5,512-GRT freighter of the Dalgleish Steamshipping Company, bound for New York in ballast. She occupied the third position in column No. 3. Her Master, Captain R. G. Phillips, had learned of Bristol City s misfortune from the Second Officer, and had hurried from his cabin to the bridge. Shortly afterwards, his own vessel was struck by a torpedo on the port side amidships, in the stokehold where the ship’s furnaces opened. There was no flash or flame that anyone could see, nor was there much of a noise. Only a modest amount of water was thrown up. But the ship’s hull was punctured to form a hole about twelve feet in diameter, with about three feet of its jagged dimensions showing above the water line. The main deck cracked amidships, and both the funnel and wireless room collapsed.

Since the W/T aerial had been carried away, too, the Wireless Operator was not able to send the requisite distress signal. Nor could the rockets be fired, because their sockets had been blown apart. The Third Engineer stopped the engines and Phillips, facing what he thought was certain and imminent sinking, ordered Abandon Ship. By 0330 three of the four lifeboats were waterborne and clear of the ship. Phillips could not get the forward raft to release, but at 0350, when he heard the hull splitting, he abandoned and joined the port motorboat. It was then early morning daylight.

Some of Wentworth’s crew were picked up from the sea, but altogether five of the forty-seven-man crew were missing, one from drowning, the rest from the torpedo’s blast through the stokehold or engine room. Among the survivors were three Navy and three Army D.E.M.S. gunners, who had been no more able to get a shot off than had their counterparts on Bristol City. By 0550 the survivors were lifted on board Loosestrife, which Phillips in his report called the Bluestrife, and now, by any name, was swollen with bereft humanity. Obstinately, the broken Wentworth continued to float well beyond the few seconds that Manke had allotted her. When HMS Loosestrifes Captain, Lt. H. A. Stonehouse, R.N.R., learned that Phillips had failed to toss overside the Confidential Books, he knew he had to sink the derelict. Accordingly, he steamed along her port side and fired a D/C close to the hull. Then, on the starboard side, he put two shells into No. 2 hold. At 0700, over four hours after Wentworth was hit, Stonehouse sent word to Phillips, who had gone below, that his ship had finally gone down.

Before HMS Loosestrife had steamed to the rescue of the Bristol City and Wentworth survivors on orders from HMS Tay, she had on her own energetically raced after U-boat targets detected by radar and asdic. On one chase she dropped a ten-charge pattern at 0517 on a U-boat that dived after being sighted on the surface, range 1,200 yards; the impact of the charges damaged her asdic recorder. During a second pursuit of a target detected first by radar at 0524, then by eye, HMS Loosestrife opened fire with one four-inch high-explosive round (H.E.) and with port and starboard 20mm Oerlikons, scoring what he thought were numerous hits with the 120 Oerlikon rounds fired. No effort was made by the U-boat to offer return fire, and after one minute it dived. At 0527 Stonehouse threw a nine-charge pattern about 100 yards ahead of the diving swirl, the last D/C of an intended ten-pattern getting jammed in the rails. Stonehouse was confident that his pattern was very well placed and a “likely kill.” The NHB/MOD reassessment has identified the target of HMS Loosestrife’s first attack as U—264 (Looks), which was undamaged; and the target of the second attack as U-413 (Kptlt. Gustav Poel), which received superficial damage. Poel, in fact, says he was not hit by any of Loosestrife’s gunfire. As for the D/Cs: “Heavy tremors in the boat, damage is slight, everything can be repaired immediately except for the main transmitter. Everyone breathes a sigh of relief!”

During the dark hours of 4/5 May, Convoy ONS.5 had passed through a Werner Henke Night, as five U-boats accounted for seven ships sunk, matching the number sunk by Henke alone on the night of 30 April/1 May. That the slaughter had not been worse, with (now) thirty-six boats assembled for attack instead of Henke’s single U-515, owed in great part to the spirited and intimidating defense mounted by the B7 defenders. Though Lt.-Cmdr. Sherwood would have no way of knowing it when he and Commodore Brook took stock in the morning—whereas in Berlin Donitz and Godt were fully aware of it from anxious W/T traffic—his band of escorts had so far damaged three boats so gravely that they made for home: U-332 (Junker), U-732 (Carlsen), and U-270 (Otto).13 These, it could be argued, were equivalents to kills so far as ONS.5 was concerned.

The escorts had severely handled two other boats, which suffered slight damage, U-314 (Auffermann) and U-413 (Poel), and they had driven off or forced to dive six more: U-264 (Looks), U-707 (Gretschel), U-168 (Pich), U-662 (Kptlt. Heinrich Müller), U-584 (Kptlt. Joachim Deecke), and U-260 (Oblt.z.S. Hubertus Purkhold). To have damaged a U-boat, even in cases where the boat was not forced to retire, was effectively to take that boat for a time out of the convoy battle, since the damaged boat had to tend more to her injuries than to her potential targets, which were passing away at seven or more knots. And to have driven off a boat, or to have forced one to dive, was also effectively to neutralize that boat’s usefulness temporarily in a night battle. It is instructive to note that none of the boats damaged, driven off, or forced to dive after 0105, when Looks got lucky, subsequently sank or damaged a ship of ONS.5. In a signal sent to the Fink boats during the forenoon of 5 May, Dönitz and Godt showed their impatience at the meager returns obtained thus far in exchange for damage. Urging the boats to use the long daylight hours for submerged attacks and for getting as far ahead of the convoy as possible before nightfall, the two German admirals urged their distant Commanders:

IMMEDIATELY AFTER NIGHTFALL THE DRUMBEAT [PAUKENSCIILAC] MUST BE TIMED TO BEGIN. HURRY—THERE ARE 40 OF YOU— OTHERWISE YOU WILL LOSE THIS CONVOY. THE BATTLE CAN’t LAST LONG SINCE THE SEA SPACE LEFT IS SHORT, SO USE EVERY OPPORTUNITY TO THE FULLEST WITH ALL YOUR MIGHT [MIT ALLER ENERGIE.]

By 0700 on the 5th, Sherwood had B7 in day stations. The convoy, now twenty-six ships in ten columns, was steering on course 202°, speed seven and a half. The weather was overcast with good visibility, the sea was moderate with swell, and the wind was westerly Force 4. In those conditions HMS Offa attempted to oil from Argon and HMS Tay from British Lady, with HMS Oribi scheduled to follow HMS Tay at the same nozzle. But at 0947, as HMS Offa closed the U.S. tanker, the Argons captain signaled that he would not be prepared to discharge fuel for another hour; and when the destroyer returned alongside at 1100 the Argons hose parted after only one gallon had passed! HMS Tay had better luck with British Lady, and HMS Oribi was able to follow at 1420. Not until 1730 in the afternoon was HMS Offa able to begin drawing 30 tons from the British tanker, slipping the tow at 1930.

These were not the ONS.5 screen’s only daylight activities. Numerous HF/DF contacts in all quadrants were acquired beginning at 0654, indicating that ONS.5 was still surrounded. We know from intercepts that the following U-boats were in contact with the convoy or its escorts during the forenoon hours: U-618, U-584, U-438, U-531 U-264, U-260, and U-378. One result was that HMS Oribi became particularly busy, followed by HMS Vidette. At 1010, HMA Oribi, in station bearing 160° 5 miles from the port wing ship of the convoy, was instructed to investigate a first-class bearing of 155° to a distance of 12 miles. Forty-seven minutes later, HMS Oribi sighted, first, diesel smoke haze, and then the conning tower of a U-boat. Increasing her speed to 30 knots, the destroyer sighted within the next 13 minutes two additional U-boats proceeding away in what seemed line abreast with the first boat. Apparently aware that they were being overhauled, all three boats dived.

HMS Oribi gained a definite asdic contact at 800 yards and attacked with four charges of a ten-pattern, the remainder being checked when the recorder tracing showed that the U-boat was passing down the port side, hence the six D/Cs left would have fallen progressively astern of it. When contact and a good trace were regained at 1243, a ten-pattern was fired by recorder and stopwatch at 1247, two minutes after which “a slight explosion followed by a heavy underwater explosion was heard, producing a bubbly eruption of water.” The quarterdeck then reported what appeared to be a periscope proceeding away from the center of the D/C scum. A third attack with five charges was carried out at 1254, with negative results, after which HMS Oribi, thinking it essential “to conserve supplies of depth charges for attacks in the vicinity of the convoy,” rejoined to fuel from British Lady and, at 1740, to resume station. In this event HMS Oribi had been in contact with four U-boats, since identified as U-223 (Oblt.z.S. Karljüng Wächter), U-231 (Kptlt. Wolfgang Wenzel), U-621 (Oblt.z.S. Max Kruschka), and U-634 (Oblt.z.S. Eberhard Dahlhaus).

HMS Vidette was stationed in position “B,” off the convoy’s starboard bow, when at 1542 she acquired an asdic contact at very close range, bearing 090°. Lt. Hart altered course to intercept the contact, which quickly was classified a submarine. Reaching the target’s position at 1544, he fired a five-pattern set to 100 feet. After opening range to about 900 yards, he swept back through the attack position, but received no further contact. HMS Vidette conducted an Observant until 1633, when she was ordered to rejoin. Hart’s assessment of his action read: “Although there was no evidence of damage to the U-boat, in my opinion the counter attack delivered probably prevented an attack on the Convoy.” The NHB/MOD reassessment doubts that a U-boat was present.

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Meanwhile, despite these efforts, another convoy ship was torpedoed. The victim was M.V. Dolius, ship No. 21 on the port-hand easterly wing. Professor Jürgen Rohwer conjectures that the assailant was U-638, commanded by Kptlt. Oskar Staudinger. A native of Löbau who had earlier (1938–1941) served in the Luftwaffe, Staudinger was one week away from his twenty-sixth birthday. We know nothing of the details of this attack, since the boat’s KTB and Schussmeldung, if one existed, did not survive the battle. The “KTB” that one does find in the archives for his second Atlantic patrol out of La Pallice, 20 April to 5 May 1943, is a reconstruction done in Berlin on or about 7 May based on his F.T.s (wireless messages), both incoming and outgoing. There is no direct evidence in the F.T.s to show that U-638 sank a ship on 5 May, and the KTB-BdU does not acknowledge receipt of such a report.

Whatever U-boat was responsible, the Dolius, a 5,507-GRT freighter of the Blue Funnel Line, was torpedoed on her starboard side at 1240. Since she was the lead ship in column No. 2 on the port-hand easterly wing, the torpedo would have had to come from very slightly ahead or from within the formation. The Master, Captain G. R. Cheetham, judged that the torpedo had been launched from close range between his vessel and the two ships, Ottinge and Baron Graham, to his starboard. With what Cheetham called a “dull” explosion with no flash, the warhead opened a 30-foot-long hole extending some 15 feet above the waterline. The concussion stopped the engines and the engine room promptly flooded, as did No. 4 hold. The Fourth Engineer and Junior Assistant Engineer were killed at their stations. The ship at first listed slightly, then came upright and began to settle by the stern. Cheetham ordered his crew to stand by the lifeboats. It was an unusually large crew: thirty-nine British and twenty-two Chinese, plus five Navy and four Army gunners.

Some of the Chinese, panicking, began lowering one of the three serviceable boats—No. 3 starboard had been destroyed—but stopped when Cheetham shouted at them. After making a thorough search for any injured, Cheetham disposed of the Confidential Books and gave the command Abandon Ship. Every man behaved with well-ordered discipline, including the Chinese, and the boats were successfully manned and lowered. As the Third Officer’s boat pulled away from the vessel, its occupants sighted a crewman still on board waving his arms for assistance. The boat returned to rescue him and another crewman was found lying unconscious below. Twenty-five minutes after the torpedo’s explosion, all the known survivors were clear of the wreck. Two engineers and one gunner were dead, one gunner died in the lifeboats, and two gunners were injured.

Two minutes after Dolius was hit, Sherwood ordered “Artichoke.” HMS Sunflower and HMS Offa responded, the corvette turning from her port bow station and charging down between columns 2 and 3 at emergency full speed. Slightly astern of the derelict, HMS Sunflower picked up an asdic contact in the center of the convoy formation, range 1,200 yards. The captain of HMS Sunflower Lt.-Cmdr. Plomer closed the position and dropped a ten-pattern D/Cs with 150-feet settings. The blasts did some damage to his own ship, but there was no sign that he had done any to a U-boat. Contact was lost, and when HMS Tay joined she could not regain, either. From circumstantial evidence, however, the NHB/MOD reassessment has concluded that HMS Sunflower s attack resulted in the sinking of Staudinger’s U-638 with all hands, at 54°12’N, 44°o5’W—swift retribution, indeed, for the loss of Dolius, and proof again of the effectiveness of Artichoke. HMS Sunflowers was the first kill made by the close escort. HMS Offa, meanwhile, obtained a doubtful contact at 1301, threw a ten-charge pattern, and rejoined the convoy.

Between 1320 and 1400 HMS Sunflower swept a circle around the sinking Dolius, then, on orders from Tay, began rescuing survivors while HMS Snowflake provided cover. Once on board, the Dolius officers, ratings, and apprentices did whatever they could to make themselves useful, serving on lookout watches, performing deck tasks of various kinds, and cleaning quarters. Plomer said later, “The ship was sorry to see them go in spite of the overcrowding involved.” As HMS Sunflower set course to rejoin the convoy, the D.E.M.S. rating who died in a lifeboat was buried overside with a short service.

Since 2244 on the 4th, the corvette HMS Pink, rather neglected in this narrative of late, has been trundling along faithfully as lone escort to a separately routed convoy of four stragglers: the American West Madaket, the British Dunsley and Director, and the Norwegian Gudvor. At 1150, ”Pink’s Party,” as the tiny fleet came to be called, was in position 54°56’N, 43°44’W, some 80 miles astern of the main body, making about 8 knots on the course, 240°, assigned by CinCWA. Twenty-seven-year-old Lt. (now Sir) Robert Atkinson, commanding Pink, was zigzagging ahead, his four charges in line abreast about 3,000 yards astern. With only 30 percent of his fuel remaining, with no chance to overtake the main body and refuel, and with a separate route that increased the distance to be steamed, Atkinson was proceeding on only one boiler, the second being banked, and had shut down one dynamo and rationed water. If an attack situation developed, he knew that the higher speeds required by those maneuvers would make greater than usual demands on his fuel reserves. But he did not quail before that prospect: not having seen any action during the voyage to date, he badly wanted a go at the enemy.

Long experienced in the North Atlantic, Atkinson had served in the Merchant Navy since 1932, and since 1937 as an officer, beginning as probationary sublieutenant, in the Royal Navy Reserve. He was called to duty in September 1939 and given command of the yacht Lorna, which, operating off Gibraltar, seized an Italian tanker when that country entered the war. He took the tanker, which was filled with seven and a half million gallons of petrol, back to England, where he asked for a “more active state of war.” Accordingly, he was sent for ASW training at HMS Osprey in Portland. That completed, he was named First Lieutenant of the corvette H.M.S. Rhododendron, which, on 21 November 1940, one month after her commissioning, became the first ship to sink a U-boat (U-104) at night. His next ship, and first corvette command, HMS Snowdrop, was detached to the “White Patrol” that ran between the northwest cape of Iceland and the packs and growlers of Greenland. There, well before Pink’s Party, he experienced the trials of a lonely vigil.

The corvette’s mission was to travel back and forth across the Denmark Strait in order to detect a breakout of the German heavy battleship Bismarck, though, as he said to the writer over a half-century later, there was not anything his “little pea shooter” could have done about it except report. “There was darkness day and night, wind and cold, a lot of frostbite seasickness all the time, poor food.” The loneliness of HMS Snowdrop’s solitary watch was deepened by the fact that “We never went ashore; the Icelanders weren’t very hospitable.” On another occasion he said: “I was always vulnerable to seasickness strangely enough, having been at sea all my life, and I recall on one occasion having so many clothes on and being so weak from seasickness, I could hardly mount the companionway to get on to the bridge, I was so physically weak.” After one month of shore duty to help him get over his seasickness, Atkinson was given command of the newly commissioned (2 July 1942) corvette HMS Pink, named after the fragrant flowers of the genus HMS ianthus. The corvette joined B7 when Peter Gretton assumed command of the Group.

Royal Navy Flower class corvette HMS Pink

HMS Pink , Flower class corvette , Flower and River class escorts were workhorse of Royal Navy and Royal Canadian Navy in Battle of Atlantic

Now, at 1154 on 5 May 1943, toward the end of the starboard leg of a zigzag, HMS Pink obtained a first-class asdic contact bearing 310°, range 2,200 yards. The echoes, Atkinson said, were “by far the clearest and sharpest I have ever heard.” The event confronted him with two conundrums: (I) Should he expend perhaps an unacceptable amount of precious fuel in making an attack, which might or might not succeed, or should he husband his oil in a simple defensive mode and thus extend his capacity to provide “scare tactic” cover for the stragglers? (2) Should he seize this opportunity to destroy one U-boat, or would his absence in so doing, whether successful or not, expose his small convoy to the torpedoes of another U-boat? The Atlantic Convoy Instructions permitted him to attack, “provided this duty can be undertaken without undue prejudice to the safety of the convoy.” Atkinson decided to attack.

At her maximum speed available on one boiler, 11 knots, HMS Pink held the contact to 150 yards, and at 1159 dropped three D/Cs, two set to 100 feet and one to 250. More were not dropped owing to Atkinson’s concern that at her low speed and with D/Cs set shallow, HMS Pink would not get beyond the blast effect. When contact was regained, HMS Pink commenced a second run in, during which her hydrophones picked up the sounds of the U-boat’s hydroplanes and/or rudder, indicating a depth change or a turn. At 1207, increasing for safety to 15 knots by getting her second boiler “flashed up,” she fired ten charges set to 150 and 385 feet. No signs of damage appeared on the surface. One minute later, a “moderately high echo” was obtained again. In setting up for a third attack, Atkinson deduced from the movements of the U-boat that it was endeavoring to put its stern and cavitation turbulence to him. As the target moved to starboard, HMS Pink followed, and at 1216, with the range at 250 yards, he ordered the firing of twenty-four Hedgehog bombs with 4° of right deflection because of wind. To his extreme disappointment, the Hedgehog mechanism misfired.

It took eleven minutes of following the plot to acquire a new contact, which was “firm and metallic,” at 1227. Two minutes later, the asdic echo was bearing 0°, range 1,400 yards. Good hydrophone effect was also heard on that bearing, and at 1233 Atkinson fired a ten-pattern set to 250 and 385 feet. With no evidence of damage, and not expecting to see any appear right away from that depth, Atkinson’s asdic team kept their sound pulses glued to the U-boat’s hull, and at 1241 contact was again “sharp and firm.” Hydroplane and/or rudder noises picked up by hydrophone suggested that the U-boat might be diving deeper. At 1244 HMS Pink made her fourth attack, ten charges set to 350 and 550 feet. This time Atkinson felt confident that he had made an accurate and successful drop. He was confirmed in that confidence during HMS Pink’s run out by hydrophone reports of blowing tanks. Then, about 500 yards astern, three huge bubbles followed by numerous smaller ones broke the surface of the water. HMS Pink turned back and closed the position to observe the “boiling”:

“… The water in the vicinity [was] considerably aerated in appearance and green and white like shallow water. Tangible evidence of destruction was greedily and most enthusiastically searched for, but nothing further was seen. It was realized that my little convoy was drawing away and was now some distance ahead and also unprotected, but I decided to risk this and to continue with the hunt.”

With asdic showing that the U-boat was quite deep and practically stationary, Atkinson decided on a second Hedgehog salvo, which was fired at 1302. But, again, the Hedgehog disappointed as all twenty-four projectiles exploded on striking the water (!) Giving the hunt one last go, Atkinson set up for another deep ten-pattern drop, commencing his run in at 1307, course 110°, speed 13 knots, eight light D/Cs fused for 350 and 550 feet, and two heavy charges with Mark VII pistols to give extra depth fused for 700 feet. (The depths were all guesses, since the Type 145 asdic then in use on corvettes did not indicate the target’s depth. The first operational depth-determining asdic, Type 147, would not be available until September 1943. It was not known that a U-boat could dive deeper than 700 feet [213 meters] until June 1943.)

Opening the range to 1,500 yards, HMS Pink listened for an echo, but there was none. Nor was there any evidence on the surface, which Atkinson returned to inspect. At 1325 he abandoned the hunt and shaped course for 240° at 15 knots to rejoin his convoy 10 miles ahead. Fourteen minutes later, HMS Pink was shaken by a powerful underwater explosion, “like a deep grunt,” which left Atkinson “in no doubt as to the fact that the U-boat was destroyed.” He was sorely tempted to turn back and see what the surface might reveal, but since his convoy had been unprotected for an hour and a half, he decided that to do so was not prudent.

Atkinson’s report on his five-pronged attack was reviewed by the Admiralty’s U-Boat Assessment Committee on 28 June 1943, and the conclusion was drawn that “this attack was probably successful and it is assessed as ‘Probably sunk.’ ” By 20 July 1943 the Admiralty was convinced that it knew the identity of the U-boat sunk: “The sinking of this submarine, which was U-192, has since been confirmed.” In the subsequent literature from Roskill to Syrett, U-192 (Oblt.z.See Werner Happe) has been identified as the fatal victim of HMS Pink on 5 May. We know little about Happe’s boat, which had sortied from Kiel on 13 April, because she was lost at some point in the battle and her documents went down with her. A KTB based on messages sent to her was reconstructed in Berlin, but it is not revealing; no response was heard by BdU since 3 May, from qu AJ 3757, and on 6 May (again on 9 May) she was declared a total loss. It is now clear that U-192 succumbed on 6 May (see below), in a sad finish to her first and only patrol.

The better fit as HMS Pink’s target is U-358 (Manke), the slayer of Bristol City and Wentworth. Analysis of the KTBs of the participating boats shows that U-358 was in the approximate same position as HMS Pink, astern of ONS.5 (U-358 at 1000: 54°52’N, 43°3o’W; Pink at 0954: 54°56’N, 43°44’W), and that over a period of one hour and a half she experienced a prolonged pounding from “69 well-placed depth charges.” HMS Pink, in fact, dropped forty-three D/Cs and twenty-four Hedgehog rockets; the latter may have sounded like D/Cs when they exploded on contact with the surface, but they would have gone off with near simultaneity. In his description of the event, Manke was not certain about the number of escorts present or about the category of his pursuer, mistaking HMS Pink for a destroyer, but he correctly cited a separate “small convoy”:

“At 1042 we sighted a small convoy: 3 steamers, 1 destroyer, and 1 corvette. The boat was heard [asdic] by the destroyer. Then 1½ hours of depth charges followed: 69 well-placed depth charges [Wabos]. The destroyer criss-crossed above the boat continuously. He must have a good hydrophone because he used asdic only for a short time before attacking. In addition, he employed doppler effect, and 50 seconds later the depth charges came.”

Afterwards, Manke surveyed the damage: diving cells Nos. 1 and 5 were out of service; the tower hatch leaked badly; there were numerous electrical breakdowns; four battery cells were cracked; there was leakage in the cooling jacket of the outer exhaust cutout; torpedo Tube 5 was inoperable for underwater launches; the stern hydroplanes could not be moved beyond 10 degrees; and the boat produced loud noises throughout the interior. After he surfaced to make what repairs he could, Manke discovered that his diesels could not produce more than 10 knots speed. He signaled a report on his condition to BdU, and at 1731 the next day he received a response: RETURN DIRECTLY TO BASE WITHOUT REPLENISHING.

It was not a kill. But it was as good as a kill. In judging U-358 to have been the U-boat involved, it is useful to note both that no other B7 or Support Group escort made a sustained attack during the time period when HMS Pink was attacking, and that no other U-boat reported being attacked during the one hour and thirty minutes when U-358 was absorbing her punishment.

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For Atkinson, elation quickly turned to ashes: “At 1453, my worst fears materialized.” About three miles astern of his small convoy, augmented since noon by the arrival of a fifth straggler, S.S. Yearby, the corvette Captain saw a “huge column of smoke” rising from the port wing ship, West Madaket, which immediately began to settle by the stern. Only one ship was sunk, but it was misfortune enough. The “another U-boat” in Atkinson’s conundrum was U—584, commanded by Kptlt. Joachim Deecke. This Type VIIC boat was a veteran of several North Atlantic patrols; had sunk a Soviet submarine (M-175) on 10 January 1942; and on 17 June (GST) of the same year had deposited four German saboteurs (all of whom were captured and executed) on the beach at Ponte Vedra, Florida. Now U-384 was submerged at 1400 on 5 May in qu AJ 5695 (5447’N, 44°12’W) :

“Enemy is in sight [by periscope], course 250°, speed 9 knots, 4 steamers, 3 of them overlapping. Enemy zigzags 20° to 230°. At 1443 I launch a 4-torpedo fanshot—Tube 4 fails to launch—at 2 overlapping steamers, bearing right 85°, range 2000 meters. The freighter in front is 5000 GRT. The one behind it is larger, and possibly, to judge from its long fo’c’s’le, is a tanker. In the foreground is a small vessel, possibly a corvette. After 4 minutes, 48 seconds, and after 4 minutes, 52 seconds, there are 3 torpedo detonations. 5 minutes and 20 minutes later there are two additional detonations, most likely boiler explosions followed by the bursting of bulkheads. After 44 minutes the first steamer sinks, and after 90 minutes the second goes down. The sinking noises are clearly made out [inside the boat]. A corvette drops warning depth charges [Schreckwasser-bomben], but they are far off.”

By this point the reader may have come to suspect that U-boat Commanders, as a species, were uncommonly given to observation errors, if not to self-deception. With claims of two sinkings instead of one, Deecke was the latest in a line that included Junker (U-332), who claimed two hits (that subsequently were credited him by BdU) when he had made none; Hasenschar (U-628), who made four claims, including a “vaporized” corvette, but had only one actual hit, plus an artillery coup-de-grace to Harbury; and Looks (U—264), with three claims and two actuals. Further, as we have seen, there have been reporting errors in ship types, in times required for vessels to sink, and in the quantity of tonnage destroyed.

Endemic to U-boat claims throughout the war were euphoric tonnage figures, as in Manke’s (U-358) claim of 8,000 tons for the 2,864-GRT Bristol City. Although Dönitz had urged his Commanders to “estimate cautiously and accurately—we are an honest firm!", they nonetheless sometimes inflated their figures either through mistaken observation, or misinterpretation of an end-of-run detonation for a Treffer (hit), or old-fashioned wishful thinking. Yet the reader would want to know that all these same defects characterized reporting by U.S. Navy submarine skippers in the Pacific war being conducted at the same time against Japan. A postwar analysis by the U.S. Joint Army-Navy Assessment Committee (JANAC) drastically reduced the number of sinkings and tonnage sunk by U.S. submarines from 4,000 enemy ships and 10 million tons claimed to 1,314 ships and 5.3 million tons actually sunk. In one individual example, the leading U.S. submarine ace of the war, Richard H. O’Kane, had his numbers reduced from thirty-one ships and 227,800 tons claimed to twenty-four ships and 93,824 tons actual.

There was only one ship torpedoed by Deecke on 5 May 1943, and it was West Madaket. A sudden jar was felt by those on board the vessel, and the Officer of the Watch and several crew members saw a large geyser of water rise on the port quarter. The torpedo must have penetrated a good distance into the hull, survivors said, because a 5-by-2½-foot hole was torn in the starboard side. Almost at once the stern sagged. Inspection of the deck, where there was a large crack in the plating amidships, convinced the ship’s Master, Captain H. Schroeder, that the freighter’s back was broken, and he ordered Abandon Ship. The entire crew of sixty-one, including twenty-two D.E.M.S. gunners, who never saw a target, made it into boats safely. In the interim, the other four merchantmen turned to starboard and performed what Atkinson called “some remarkable and spectacular zigzags.”

When HMS Pink caught up to West Madaket, he carried out an Observant, dropping D/Cs intermittently to keep the U-boat down. These were the “warning charges” heard by U-584. The lifeboats were widely scattered and Atkinson endeavored to muster them so that he could make a pickup of survivors while hove-to in the shortest possible time, knowing full well that Pink would make an inviting target during the operation. When he approached the boats and found them filled with as much luggage as humanity, he ordered the men out and the luggage left. Then he told the Oerlikon crews to use the boats and luggage for practice fire. Finally, by 1600, without hindrance, he had everyone on board, and could turn his attention to the canted hulk of West Madaket.

Although her Confidential Books were safely overboard in a metal container, Atkinson decided to assist the broken merchantman to sink, which he accomplished by firing down her side two D/Cs set to 50 feet from his starboard throwers. “The result was devastating,” he stated four days later. “She split as if cleaved by an ax amidships, sinking in two separate pieces and turning turtle as she sank.” (To the writer he said, dryly, “That U-boat didn’t sink West Madaket. I sank her.”) Atkinson was surprised that she left no trace of her passing despite the fact that her bunkers contained 540 tons of oil. Now Pink set course to catch up with her remaining four charges while her crew busied themselves making room on the tiny corvette for threescore American passengers.

During the daylight hours of 5 May, two functioning merchantmen, Dolius and West Madaket, were torpedoed. But in exchange, the Germans took a beating of their own. HMS Sunflower sank U-638 (Staudinger), and Pink mauled U-358 (Manke), which was compelled to move off for return passage. On the same day, in a reprise of the U-439/U-639 collision on 4 May, U-600 (Kptlt. Bernhard Zurmühlen) slammed into U—406 (Kptlt. Horst Dieterichs) at 0905 in qu CG 1746, off the coast of Spain, necessitating the return of both boats, which, like U-439 and U-639, had occupied adjacent stations in Group Drossel. The accident took place with the two boats on the surface in good visibility (gute Sicht), seas Force 3–4 with medium swell. Unaccountably, U-600 came into view on U-406’s port side and took a collision course toward the latter boat, which frantically flashed a recognition signal (Erkennungssignal) and turned hard-a-starboard, both engines emergency full (äußerste Kraft voraus!). Without deviating, the bow of U-600 rammed into U-406’s hull just forward of the port diving tank. Both boats were compelled by the damages inflicted to make a Rückmarsch, U—600 to La Pallice, U-406 to St.-Nazaire.

The first U-boat kill by a surface escort had been posted, and the list of damaged and retreating U-boats was lengthening. So, too, was the list of sunk merchantmen, of course, but the ONS.5 hemorrhaging was about to stop, following one last, and spectacular, U-boat success. Three weeks into her second North Atlantic Feindfahrt, the Type VIIC U-266 launched four torpedoes in rapid succession at 1950 on the 5th. We have no details of her attack because the boat, with her documents, was destroyed later in the month. A KTB reconstructed in Berlin based on F.T.s received cites this signal from boat commander Kptlt. Rolf von Jessen:

“Sank one [ship] of at least 5000 GRT and a second, based on sinking noises, probably also 5000 GRT. Two further detonations were definitely heard. At 2150 [GST] the enemy was positioned at AJ 8359, course 200°, speed 7 knots.”

Three ships were hit in this action: British steamers Selvistan and Gharinda, followed by the Norwegian steamer Bonde, at 1,750 GRT the smallest ship in the convoy. What Sherwood called “reliable survivors” from the British vessels reported that the torpedoes were seen approaching from port. Since the three victims were positioned toward the starboard side of the convoy, indications were that U—266 had penetrated inside the columns. That Bonde was two columns farther toward the convoy’s center, and that her survivors sighted and engaged a periscope on the starboard beam, persuaded Sherwood that the U-boat torpedoed the British vessels with his bow tubes and the Norwegian with his stern.

First hit was the 5,136-GRT Selvistan, owned by the Hindustan Steamship Company of Newcastle, whose First Officer, Mr. C. D. Head, was on the bridge at the time. To port side he sighted something moving near the surface that he took to be a porpoise, since it was “spouting water.” It crossed in front of Argon’s bow in the adjoining column and then, halfway to Selvistan, it leaped above the surface, revealing itself to be a torpedo. Head described it as “silvery grey,” and thought that because of its slow speed, perhaps 10 to 12 knots, it was nearing the end of its run (G7a torpedoes normally ran at 40 knots, G7es at 30). Though he rang Full Speed Ahead and put the helm hard to port, the ship lacked sufficient speed to swing clear and the torpedo impacted the port side with a dull explosion in No. 5 hold, showing no flash, but sending hatch, beams, and ballast skyward. No more than five seconds later, a second, unseen torpedo punctured the No. 4 hold with exactly the same effects and result.

Quickly, the steamer settled by the stern, and in a matter of only two minutes submerged from view. In that fractional amount of time it was not possible to lower either of the two main lifeboats, but the Master and crew did manage to launch two small bridge boats and the forward starboard raft, on which, or clinging to which, they floated off. Five crewmen were declared missing and one other man, a D.E.M.S. gunner, had a grave head wound from which he would die before rescue. First Officer Head stated later that the Indian firemen, who were the only men to share his boat, “were simply no use at all; they just sat in the boat, praying to Allah to save them, but not attempting to do anything to save themselves.” Fortunately, after three-quarters of an hour, the forty men who survived were lifted on board the frigate Tay. Since HMS Tay’s asdic was inoperable, Sherwood had assigned his own vessel to the rescue mission while directing HMS Offa and HMS Oribi to carry out Observant around the sinking position.

Second to be hit by U-266 was the 5,306-GRT Gharinda, owned by the British India Steam Navigation Company of Glasgow. This freighter, with a large crew of ninety-two, including six Navy and four Army gunners, had straggled on 3 May, owing to heavy weather, and had not regained contact with the convoy until 1100 on the 4th. “About two minutes” after Selvistan was torpedoed, Gharinda s Master, Captain R. Stone, estimated, this second British vessel was struck by a torpedo in No. 1 hold on her port side. There was a flash, a very loud explosion, and a towering column of water that rained down on the bridge, carrying with it the hatches of No. 1 hold. The force of the explosion twisted both derricks and blew them over to starboard. Since the ship began to settle rapidly by the head, Stone threw overboard the Confidential Books and rang Abandon Ship. Five of the six lifeboats were successfully lowered except that, owing to a crewman’s error, one of the five nose-dived into the sea and swamped.

Stone made a quick inspection of the ship to make sure no one had been left behind, then joined one of the boats. A short time later, he entertained the notion of returning to his ship to see if she could be saved, even though the propeller and rudder were out of the water. The notion, however, was doused by Tay, which arrived on the scene and began “hauling up” the survivors; Stone related tersely that he had been “hauled up by the scruff of my neck.” Sherwood told Stone that he could not indulge him in his desire to return, because he had to go after the survivors of Bonde, which also had been torpedoed. Bereft because of the loss of his ship, Stone could have drawn comfort from the fact, had he known it, that his was one of only two ships torpedoed in ONS.5 that did not lose a single man. If First Officer Head was disappointed with the performance of his Indian crewmen off Selvistan, Stone was favorably impressed by his own sixty-eight Indians, of whom he said:

“I am extremely pleased with the native crew, because they showed no sign of panic at any time. I think this is partly due to the fact that on board my ship no English is spoken, all orders are given in the language of the natives, which I consider helps them to understand what is going on, and therefore they are not liable to panic. I would specially like to mention the Indian Quarter Master, Shareatullah, son of Aboth Allee, who in spite of the debris which was falling on the Bridge, remained at his post at the wheel until ordered to his boat by me.”

The thirteenth and final ONS.5 merchantman to die at sea was bantam Bonde in column 8. Chief Officer M. MacLellan of S.S. Baron Graham remembered:

“The Bonde was the little ship we all admired so much in that convoy. In such a vast expanse of sea, she looked so tiny as she courageously battled through the heavy weather, frequently disappearing from view completely in the heavy seas and swells. The first thing I used to do as daylight broke in my morning watch was to look for our little friend, and if she was still bobbing along the day was made.”

To Captain Stone of Gharinda we owe our knowledge of what happened to Bonde. Just after his own ship was torpedoed, Stone was on the bridge about to throw his Confidential Books overboard when he saw the Oerlikon gunners on Bonde open 20mm fire against a periscope sighted close on her starboard beam. It was the first time in ONS.5’s voyage that D.E.M.S. gunners engaged a U-boat. Stone ordered his own Oerlikons to fire in the direction where Bonde s shots were splashing. A few seconds later, he saw and tracked a torpedo wake approaching Bonde s starboard side. The nearby Vidette also reported seeing torpedo tracks on the steamer’s starboard beam. “Then,” said Captain John Gates of Baron Graham, who was also watching, “there was an explosion and [Bonde] seemed to jump up in the water. When the smoke and spray of the explosion had cleared away, the Bonde was already standing on her end with her bow and foredeck vertically out of the water. I looked away for a few seconds and in that time the ship sank.” There had been no time to lower boats or rafts. When Tay came around to pick up survivors she found only twelve men from the crew of thirty-eight.

Alarmed by the sudden loss of three ships, Commodore Brook ordered an emergency turn of 90° to port, which was executed successfully beginning at 1950. He would resume base course at 2045, at which hour Sherwood ordered the escorts to resume station, excepting HMS Offa and HMS Oribi, which had been conducting Observant around the sinkings. At 2039 HMS Offa gained a firm asdic contact and during the next hour and 38 minutes made five large-pattern attacks. HMS Oribi joined in the hunt but was unable to acquire contact. McCoy’s onslaught resulted in extensive damage to U-266, the slayer of Selvistan, Gharinda, and Bonde. Kptlt. von Jessen reported suffering damage to diving tank No. 3, trim cells, Junkers air compressor, and starboard dynamotors. Forced to move off for repairs, the boat never rejoined the Fink line, eventually being sunk by an aircraft on 15 May. With no evidence of a kill or damage, HMS Offa broke off the action and shaped course for the convoy, taking Oribi with her. Explained McCoy: “Heavy W/T activity indicated that the convoy was threatened with annihilation and I considered it imperative to return to it before dark.”

In the meantime, at 1954, a VLR (Very Long Range) B-24 Liberator, Aircraft J/120 from RAF Coastal Command came out from Reykjavik, appeared overhead and made R/T contact with Sherwood. Its appearance gladdened everyone in the convoy. Sherwood asked the pilot to search astern for stragglers and wrecks. This the Liberator was able to do for only 45 minutes until, reaching PLE, the pilot and Sherwood had this exchange: Aircraft: “Don’t want to go, but have to.” Tay. “Thank you for your help.” Commodore Brook observed that this Iceland-based bomber was the first air escort he had seen since 2 May, “though air support was so sadly needed.” (He must have missed seeing the B-17 Fortress from Gander on the 3rd; the two Cansos (PBY Catalina flying boats) from Gander on the 4th were too distant to be seen.) He might have wondered, though, why he was not seeing aircraft from Newfoundland at this hour late on the 5th, when Gander and Torbay were not far distant. An RCAF Canso of Eastern Air Command did sight four “single vessels,” probably stragglers, between 0810 and 0845 earlier in the day but made no contact with ONS-5’s main body. A second Canso intended as escort for the convoy crashed on takeoff from Gander, killing five crew members. According to a message from RCAF headquarters in Ottawa on 7 May, a B-17 Fortress from Gander met ONS.5 during a ten-hour sweep on the 5th, though its presence was not observed by either Sherwood or Brook. The message containing this information about the Canso and the Fortress was sent to Washington to counter “comment” in the U.S. Navy Department that, “Apparently there was no air support for ONS.5 on 5 May and this [was] assumed to be due to weather.” The RCAF response essentially agreed that foggy weather was the reason.

At ONS.5’s position the Atlantic surface was calm, there was no wind, and the air was heavy with drizzle and mist. The convoy ships in contact with the Commodore numbered twenty-three in ten columns, on course 202°. As darkness embraced the wrinkled sea and a high volume of HF/DF activity engaged HMS Tay s receivers, Sherwood once again deployed his close escort forces for nighttime vigil: HMS Tay ahead, his broken asdic on listening watch only; HMS Sunflower on the port bow; HMS Vidette on the starboard bow; HMS Snowflake on the port quarter; and HMS Loosestrife on the starboard quarter. The port and starboard beams were uncovered. HMS Pink was still occupied with her small flock astern, and the two EG3 destroyers HMS Offa and HMS Oribi were assigned to positions five miles out on each bow. At BdU in Berlin, Admirals Donitz and Godt were drawing up their own plans for the night, expressed in four W/T exhortations to the Fink boats, of which fifteen are known to have been in contact with the convoy in the evening and early nighttime hours.

HASENSCHAR CONVOY BOATS SHOULD REPORT THEIR CONTACTS AND POSITIONS MORE FREQUENTLY.ALL ARE TO MAKE THE MOST OF THE GREAT OPPORTUNITY TONIGHT OFFERS.TO THE MEASURE THAT THEIR ANTI-AIRCRAFT ARMAMENT IS IN ORDER BOATS ARE TO STAY ON THE SURFACE AND FIRE WHEN AIRCRAFT APPEAR. THE AIRCRAFT WILL THEN SOON CEASE TO ATTACK.IF THERE ARE NO MORE MERCHANTMEN THERE TO BE SHOT UP SINK THE ESCORT VESSELS MAKING FULL USE OF MAGNETIC EXPLODERS.

The mist of early night thickened to fog and drizzle. The U-boats could be seen, phantomlike, mustering on the surface. Tay sighted seven boats in close proximity. They may have been the same seven seen by Günter Gretschel in U-707:

“I am positioned within sight of seven boats, in front of the convoy. I wanted to make a joint attack in the darkness. Unfortunately, the weather has thwarted our plans. The visibility has gotten very bad, with fog and drizzle, and this makes any attack impossible in the pitch-black night.”

Gretschel and the weather notwithstanding, between the hours of 2252 on the 5th and 0947 on the 6th the Fink boats made no fewer than twenty-four attempted attacks on the convoy from every direction except ahead. And at battle’s end the night did not belong to the U-Bootwaffe, as Berlin had expected. Instead, thanks to a dense fog bank, to shipborne centimetric radar, and to the pluck and skill of the escort Captains, the night belonged to the Royal Navy, which not only protected ONS.5 and HMS Pink’s Party from further harm, but sank four of the U-boat attackers and damaged and repeatedly drove off other boats or forced them to dive.

The escorts made twenty attacks of their own during the hours named. Every ship of B7 and EG3 was engaged, churning at full speed across the ocean surface in this direction or that, throwing and dropping D/Cs, firing guns, or ramming, then quickly rejoining the screen. Ships of First Escort (Support) Group, when they came on the scene at 0600, similarly threw themselves at the enemy with great energy. In the midst of which actions Commodore Brook ordered another convoy emergency turn, 90° to starboard at 2310, resuming course at 2336, and evasive turns to 186° at 0100 and to 156° at 0200, in conditions when visibility was one mile by 2202 and 100 yards by 0100! Around and inside the convoy columns, combat was fierce, continuous, and confusing. Proving that sea warfare is one of the most confounding of human activities, the night of 5/6 May proceeded in such seeming disarray that at its conclusion, Sherwood threw up his hands and conceded, “It is quite out of the question to give a detailed account in chronological order.”

In the narrative that follows an effort will be made to place a template of order over the tortured seascape by focusing on the principal actions of individual escorts, while leaving aside the parries and thrusts that had no known results. Throughout, it bears keeping in mind that whereas the shipborne Type 271 RDF (radar) oscilloscopes were displaying to Sherwood’s men bright, clear U-boat echoes that conveyed enemy positions and ranges, the U-boat Commanders, lacking comparable equipment, were groping about blind. Said Günter Gretschel on U-707: “Surfaced, pitchblack night, fog, can’t see your hand in front of your face” [Hand nicht vor dem Augen zu sehen].

Advantage: U.K.

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7 BEYOND ALL PRAISE

The Battle for ONS.5

In the submarine war there had been plenty of setbacks and crises. Such things are unavoidable in any form of warfare. But we had always overcome them because the fighting efficiency of the U-boat arm had remained steady. Now, however, the situation had changed. KARL DÖNITZ

The seven-day battle fought against thirty U-boats is marked only by latitude and longitude and has no name by which it will be remembered; but it was, in its own way, as decisive as Quiberon Bay or the Nile. CAPTAIN STEPHEN W. ROSKILL,D.S.C., R.N.AT 2309*

ON THE 5th, HMS Vidette was in escort position “C,” starboard bow of a fog-blurred convoy anxiously keeping station by whistle, when she acquired a radar contact nearly dead ahead bearing 200°, range 5,100 yards. Hart sounded action stations, altered course slightly, and increased speed to 18, then to 20 knots. At 2317 a second, smaller echo came in from a radar contact bearing 190°, 7,200 yards. Six minutes later, Hart sighted a U-boat ahead steaming away at high speed. Directly after the sighting, the U-boat commenced a dive and by 2325 it was fully submerged 700 yards ahead. Hart ran over the still-visible diving swirl and at 2326 fired the first of a ten-charge pattern; the tenth D/C left the throwers 25 seconds later. Nearly a minute after the last gray geyser, the bridge personnel, D/C crews, and engine room ratings heard a large underwater explosion, after which members of the D/C party as well as the Engineer Officer at the top of the engine room hatch observed a dark column of water rising between 300 and 600 yards astern.

Hart considered the U-boat to be seriously damaged if not destroyed. The NHB/MOD reassessment credits him with the destruction of U-531, a Type IXC/40 boat commanded by Kptlt. Herbert Neckel. Launched only nine months earlier by the Deutsche Werke yard at Hamburg, U-531 was on her first war cruise, having sortied from Kiel on 13 April. Two and a half hours earlier, this boat had reported sighting two destroyers in qu AJ 8368. Neckel, a native of Kiel, had earlier served under Kptlt. Fritz-Julius Lemp on U-30, which had sunk the British passenger liner Athenia on the first day of the war, with the loss of 112 passengers. Now his war was over, too.

Instead of seeking an asdic confirmation, Hart went after the second radar contact, which was then at range 2,000 yards. Reaching 900 yards, he sighted the U-boat, which soon after appeared to alter course 30° to starboard and to dive. At 2333 Hart laid a five-charge pattern over the submerged boat’s estimated position. After opening range to 1,200 yards, he returned to sweep the area by asdic, but made no contact. While returning to his escort station, he swept the position of his first attack, but there, too, he made no contact. It may well be that one of the U-boats known to have been damaged this night suffered that hurt from HMS Vidette’s second attack, probably U-707 (Gretschel), which recorded suffering D/C damage at about that time.

After resuming station at 0125, HMS Vidette went an hour without a contact, until at 0226 radar showed a U-boat bearing 230°, range 1,500 yards. Increasing speed to 20 knots, Hart altered course toward the target, but just past range 700 yards the radar echo disappeared into the ground wave. Starshell fired was of little use in the existing fog, but Hart dropped one D/C set to 50 feet just to assure the intruder that he was not being ignored. Back in station, HMS Vidette obtained, and pursued, two other radar contacts, at 0310 and 0341, but with no better luck than she had on the 0226 chase.

Then, at 0406, when the destroyer was sweeping back to the convoy screen, her luck changed. The asdic operator reported a contact. One minute later, the contact was classified as “submarine,” bearing 097°, range 800 yards. Hart decided to attack with the Hedgehog, and at 700 yards he told the H.H. crew that he would give the order to fire by voice pipe, since, owing to electrical shorts caused by water penetration, the fire buzzer was not reliable. The recorder showed a relative speed of approach to the target of nine knots; it showed, furthermore, that the U-boat was moving slightly to the right, calling for a deflection of 3° right on the projectile pattern. With the last center bearing at 108° and the gun put at iii° to allow for a 3° throw-off to the right, Hart gave the fire order at 0408.

All twenty-four H.H. bombs were successfully fired and there were no prematures on impact with the water. About three seconds after the last splash, lookouts heard two distinct underwater explosions—H.H. projectiles, which were not fused for depth, did not ordinarily explode unless their nose pistols struck a solid object—and, furthermore, observed flashes. Shortly afterward, the Asdic Control Officer reported “very loud” blowing of tanks and “metallic banging noises.” As HMS Vidette maintained course and speed, the First Lieutenant and the D/C party reported that the U-boat appeared to be surfacing on the starboard side. It did not do so, but on that side there was a pronounced disturbance on the surface that Hart thought was caused by air escaping the U-boat.

Asdic contact was lost at 120 yards past the point of attack, and though the point and surrounding area were reswept, contact was not regained. No debris appeared on the surface, but Hart was certain on this one: “In my opinion this U-boat was destroyed.” And he was right. The boat was U-630, commanded by twenty-eight-year-old Oblt.z.S. Werner Winkler, a native of Wilhelmshaven and a product of the “Olympic” Kriegsmarine officers’ class at Flensburg-Mürwik in 1936. A Type VIIC boat, still on her first-ever combat patrol, U-630 had one merchantman to her credit, the British frozen-meat ship Waroonga, sunk with the loss of seventeen seamen during B7’s escort of HX.231 in early April. Now U-630 herself plunged into the locker with twelve unexpended torpedoes and forty-four untold stories of froth-corrupted lungs.

At 2326, while steaming on the convoy’s starboard beam, the corvette HMS Loosestrife obtained a radar contact bearing green (starboard) 8o°, range 4,700 yards. Her captain Lt. Stonehouse altered course to pursue and eight minutes later, sighting the contact moving from right to left on the surface, opened up with Oerlikons and one four-inch round at a range of about 800 yards. The 20mm tracers could barely be seen through the fog caroming off the enemy’s tower and upper hull, as the U-boat careened like a wraith through a catacomb, and then dived. Asdic contact was gained at 300 yards and the corvette attacked it with a ten-charge pattern by recorder trace. The NHB/MOD reassessment believes that the target was U-575 (Kptlt. Günther Heydemann), which was undamaged. With no visible result, HMS Loosestrife resumed station at 2345. Another radar contact soon after proved to be HMS Vidette.

At 0009, in a reshuffle on the convoy screen, Stonehouse was ordered to transfer his vessel to position “H for Harry,” starboard quarter in A.C.I.'s screening diagram N.E.6, which was his very good luck, since in that position, at 0030, he detected the boat that he would kill: U-192, a Type IXC/40 on her first patrol. Commanded by Oblt.z.S. Werner Happe, a native of Alfeld/Leine, south of Hannover, and a graduate of the “Olympic” class of 1936, U-192 had sortied from Kiel, Germany, on 13 April, and on 1 May, in qu AJ 3797, had launched a torpedo that missed one of the ONS.5 merchantmen, identity not known. Now, at 0030 on 6 May, U-192 appeared as a small pulse echo on HMS Loosestrife’s radar set, bearing red (port) 95°, range 5,200 yards. Stonehouse rang up emergency full ahead and went after it.

Six minutes later, the blurry form of Happe’s boat came looming before the lenses of Barr and Stroud Pattern 1900A 7 x 50 binoculars on board Loosestrife, where lookouts called out the range—500 yards— which was a remarkable sighting given the fog. Just as remarkable, Happe’s lookouts apparently sighted the corvette at the same instant, since the U-boat abruptly turned to release the venom in her tail, launching two torpedoes from stern tubes, and then commenced a “violent zigzag” ahead. HMS Loosestrife’s gun crew loaded the four-inch with H.E., but held their fire since Stonehouse’s intention was to ram.

At 0040 U-192 commenced an alarm dive on about the same course very close ahead. As she did so, HMS Loosestrife ran directly up her wake. Failing to make ramming contact, Stonehouse fired a ten-charge pattern set shallow. When the D/Cs released their anvil-like blows, the U-boat was observed to break surface, where, seconds later, she shuddered from an interior explosion. The mortally wounded frame was enveloped in a “greenish-blue” flash, which was the description given by several on board the corvette, including two lookout numbers specially posted aft to confirm results. The officer in charge aft watch also saw debris thrown up from the U-boat. Inside the corvette’s engine room and boiler room the deck plates lifted in reaction to the explosion, leading some of their occupants to fear that Loosestrife’s stern had been blown off. After Stonehouse turned to investigate, his First Lieutenant and Yeoman of Signals saw “an immense patch of oil spreading from port hand to starboard bow” as well as floating debris. In combination, the explosion, oil, and debris constituted as definite a confirmation of destruction as Stonehouse was likely ever to get, excepting the retrieval of a Commander’s white cap. While his after-action report does not mention it, one may suppose that after so long an ordeal at sea, there was prolonged hearty cheering by ship’s company. Certainly we know there was elation among HMS Loosestrife’s passenger list of twenty-nine survivors from Bristol City, whose Master, A. L. Webb, said: “The whole action was extremely exciting, and all my crew thoroughly enjoyed themselves.” U-192 sank with all hands. Stonehouse then set a course of 200° to the convoy, where he resumed station at 0105.

HMS Vidette

V-class Royal Navy destroyer HMS Vidette , credited with two U-Boat kills during passage of convoy ONS.5

The next success belonged jointly to HMS Oribi and HMS Snowflake. First, HMS Oribi. This EG3 destroyer was in station five miles on the convoy’s port bow when, at 0252 her asdic operator reported, “Echo bearing green thirty—close.” Lt.-Cmdr. Ingram had to make an “instantaneous decision” whether this contact was a U-boat or the corvette HMS Sunflower, which was thought to be nearby. Since he had no radar contacts to starboard, where HMS Sunflower would have shown up as a blip, Ingram swung his ship to that heading, where, with huge relief, he sighted not the corvette but a U-boat sliding out of the fog about one cable (608 feet) on the starboard bow, steering from right to left. It was a perfect plot for a ram, and Ingram’s bridge braced for the impact. Oribi had been proceeding at 22 knots, but her speed now was somewhat attenuated by the drag met on turning to starboard. As the destroyer bore down, the fo’c’s’le hid the U-boat’s conning tower, and the stem plowed into the enemy hull probably abaft the tower. The force of the collision slewed the boat around to port side, where, in Ingram’s words, “she heeled over with her bows and conning tower out of the water.” While a shallow D/C pattern had been ordered, there was no time to get it off; furthermore, the impact of the ramming had broken the light that illuminated the clock and plot.

Worried about damage to his bows, Ingram ordered slow both engines and asked for reports. The forepeak and lower central store were flooded, he learned, but the flooding was contained by a still watertight bulkhead abaft. The asdic dome it was found by trial was slightly damaged, but there was no interior evidence of underwater damage to the hull. At 0310 a still seaworthy HMS Oribi turned to port and searched for wreckage from the U-boat. Visibility had improved to about two cables, but lookouts found no sign of the ramming victim except for “a very strong smell of oil over a very wide area,” indicating a puncture of the U-boat’s portside fuel bunkers. At 0314 the asdic operator reported both asdic and hydrophone contact with a U-boat at green 50°, range 1,100, and Ingram pursued, though at a reduced speed of 12 knots, since the forward bulkheads had not yet been shored. At 0318, by stopwatch, HMS Oribi dropped a single charge, set deep, on the last estimated position. At 0332 the search was abandoned, and Ingram shaped course to resume station, at which he had no further actions during the night.

Said Ingram in his report of the ramming: “Taking into account own ship’s speed and the damage sustained by herself, together with the force and angle of impact I have no doubt whatsoever that this submarine was sunk.” It was a perfectly reasonable conclusion, one that was concurred in by the Admiralty’s U-Boat Assessment Committee, on 21 June 1943. In fact, however, the U-boat struck, Type IXC U—125(Folkers), survived the ramming, though with serious damage rendering her unfit to dive. At 0331, Kptlt. Folkers reported his plight to BdU: HAVE BEEN RAMMED—AM UNABLE TO DIVE. QU AJ 8652. REQUEST ASSISTANCE. COURSE 90 DEGREES; and heard back assurances from nearby boats U-552, U-381, U-413, U-260, U-614, and XJ-402 that they were proceeding to his succor. Three hours later, at 0625, BdU ordered only the first four boats named above to tend to the needs of Folkers and his crew; the latter two were to remain on operations. The four rescue boats hunted for Folkers until the morning of the 7th, when they reported failure and broke off to refuel from the tanker U—461 in the adjoining Marinequadrat AK 89 directly to the east.

Enter HMS Snowflake, which made the BdU rescue order moot. This corvette earlier, at 0231 and 0238, had dropped three heavy charges on U-107 (Gelhaus) as scare tactics. At 0330, while in station R, on the port quarter, Lt. Chesterman received a radar echo bearing 030°, range 4,100 yards, and, after advising HMS Tay, commenced a chase. Fog had closed the visibility to one mile, and starshells were useless, so when he had closed to gun range, Chesterman directed four-inch fire at the target by radar alone. At 0340, the U-boat, which had been working to southward, dived before being sighted. Snowflake immediately obtained asdic contact at a range of 400 yards. Running over the contact at 0341, Chesterman dropped his penultimate D/C, a heavy charge set to 140 feet.

At the moment of dropping, HMS Snowflake acquired a second radar contact bearing 170°, range 2,400 yards, moving rapidly left. Chesterman altered course to intercept and again engaged with the four-inch. While firing, HMS Snowflake received yet a third radar echo bearing 185°, range 1,000 yards. Fearing a torpedo attack by this third, nearby boat, Chesterman broke off his gun action against the second boat and turned to attack the third, which immediately dived. With asdic contact bearing 16o°, range 700 yards, Chesterman began a run in with his last D/C, but for some reason the asdic operator lost the contact before an attack could be made. Meanwhile, at 0349, HMS Tay, to whom Chesterman had been reporting his three pursuits, signaled by R/T: “Sunflower assist Snowflake.”

HMS Snowflake then began an asdic and radar sweep through the last known positions of the three submerged boats. Chesterman commanded the operation from his action post in the center of the compass platform with, to his left, voice pipes to asdic and plot, and to his right, voice pipes to radar and plot. At 0354, radar picked up a fourth boat— on the surface, low in the water, and apparently stopped, since the range was closed rapidly. Visibility was bad. At 0400, when range had decreased to 100 yards (!), Chesterman ordered on the starboard searchlight. Its sword of white light revealed directly ahead a U-boat heavily damaged about the conning tower, under power though, working rapidly to starboard. Chesterman ordered the wheel put hard-a-starboard with intent to ram, and opened fire with every available weapon that could be brought to bear, scoring a number of hits. The U-boat averted being rammed head-on, but Snowflake, maneuvering inside the U-boat’s turning circle, came to dead slow alongside its starboard side, where only a few feet separated the two vessels, and illuminated its tower and deck with the port searchlight and ten-inch Signal Projector.

That close, Chesterman could see that the enemy boat was down by the stern, the tower was crumpled, the periscope standards were warped, the flak guns were crippled, and the after hatch cover had been blown off. That close, too, HMS Snowflake ‘s guns could not be depressed enough to continue fire, so Chesterman ordered a slow withdrawal. As the corvette drew back, the U-boat settled farther by the stern, causing air bubbles to rise from the submerging after hatch. Some German crewmen abandoned the boat at this point; some others lined the foredeck; but a few, more determined and belligerent, or perhaps more desperate, made for the forward deck gun. That endeavor was frustrated by HMS Snowflake s port Oerlikon and 40mm pom-pom guns. An officer was seen on what remained of the tower, waving his arms as a sign of ceasefire or surrender. When this was ignored, the rest of the crew went into the sea.

The U-boat’s sinking led Chesterman for a time to think that in coming alongside, his port bilge keel had rammed the U-boat’s starboard side, but on closer view he found that this was wrong. Suddenly five scuttling charges were heard from the sinking U-boat, the first charge louder than the rest. Sweeping with lights through the survivors, HMS Snowflake saw some in a small dinghy, but most swimming singly through a large oil patch. Since HMS Sunflower was now present, Chesterman thought that the survivors might be taken on board the two corvettes and delivered to St. John’s for interrogation, and he so suggested to HMS Tay. Rescue, no doubt, was what the German crew was expecting when they scuttled. Sherwood’s reply by R/T was as fatal as it was laconic: “Not approved to pick up survivors.” Though Sherwood offered no reason, it is probable that he considered it too dangerous for the corvettes to remain stationary, rescuing survivors in the middle of an ongoing battle.

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In the following minutes one of HMS Snowflake’s searchlights revealed Sunflower dangerously nearby, and both corvettes put wheel hard to avoid collision, which would have been a doubly sad event, since the Australian Chesterman on HMS Snowflake and the Canadian Plomer on HMS Sunflower commanded “chummy” ships, so much so that in B7 they had become known as HMS Snowflower and HMS Sunflake. Leaving then the forty-eight-man crew of U-125, for it was the same boat that had been rammed by HMS Oribi, to bob upon the corpse-ridden sea, HMS Snowflake, with HMS Sunflower, steamed off to other echoes. The panische Angst felt by the U-boat crew, who watched from meager flotage the withdrawal into fog of their only earthly hopes, is, of course, beyond verbal expression.

HMS Snowflake’s R/T log for the attack period fairly crackles with the teamwork displayed by the two corvettes:

TO TAY FROM SNOWFLAKE:“R.D.F. contact eight o’clock.” 0330.“U-boat dived, chasing another.” 0340.“Second U-boat dived, chasing third.” 0345.“Am attacking with charges—last charge.” 0346.

TO GROUP FROM TAY: “Sunflower assist Snowflake.” 0349

TO TAY FROM SNOWFLAKE:“Not attacking with charges. All three dived. Am not in contact. Resuming station.” 0330.

TO SNOWFLAKE FROM SUNFLOWER :“Do you wish my assistance?” 0332

TO SUNFLOWER FROM SNOWFLAKE : “Yes. R.D.F. contact bearing two-six-zero degrees, three thousand yards from me.” 0334.

TO SNOWFLAKE FROM SUNFLOWER:“I will pass round you and investigate.” 0336.

TO SUNFLOWER FROM SNOWFLAKE:“Have rammed U-boat. Please join me.” 0401.“Areyou in contact with me?” 0403.

TO SNOWFLAKE FROM SUNFLOWER:“Am proceeding in your direction.” 0403.

TO TAY FROM SNOWFLAKE:“Shall I pick up survivors?” 0407.

TO SNOWFLAKE FROM SUNFLOWER “Am in contact with you, three-one-five degrees, three-five-zero-zero yards.” 0410.

TO SUNFLOWER FROM SNOWFLAKE:“Investigating another echo and leaving survivors.” 0411.

TO SNOWFLAKE FROM Tay:“Not approved to pick up survivors.” 0412.

TO SNOWFLAKE FROM SUNFLOWER:“Am in your immediate vicinity.” 0413 [the time of the near collision].

TO SUNFLOWER FROM SNOWFLAKE:“Sorry. Am resuming my station. Glad none of yours hurt. Have one charge for one more.” 0417.

TO SNOWFLAKE FROM SUNFLOWER:“Nice work. Don’t mention it. Where shall we go next?” 0418.

After that exchange, HMS Snowflake dropped the last D/C in her stowage and resumed station.

Since HMS Offa’s five attacks earlier that night from 2039 to 2218, this EG3 destroyer had rejoined the convoy on the starboard bow; assisted HMS Vidette, who was giving three U-boats a headache around the midnight hour; proceeded over to the convoy’s port bow to provide cover for an alteration of course to 156° at 0200; gained, regained, then lost a radar contact; and finally, at 0300, regained and held the contact, bearing 258°, range 4,400 yards. The amplitude of the echo received on HMS Offa’s as Type 272 RDF equipment plainly indicated a U-boat, which the destroyer’s plot showed to be proceeding at 12 knots on a course of 190°. Captain McCoy increased speed to 20 knots and set a course of 210° to intercept. At 0312, with range at 500 yards, radar contact disappeared in the ground wave, but hydrophone effect picked up the characteristic high-pitched rattle of fast diesel engines on the same bearing. At 0314, the effect grew fainter, leading McCoy to assume that the U-boat had dived. HMS Offa altered course slightly to starboard, and soon after, lookouts sighted a wake. The boat had not dived after all, and hydrophone effect became loud again. McCoy hauled out to port clear of the wake, took a course parallel to that of the boat, and at 0315 ordered the twenty-inch Signal Projector switched on.

Brightly illuminated on the starboard bow at 100 yards was a light gray-painted Type VIIC U-boat, trimmed down, with after casing awash. Abaft the tower was “a metal framework,” which would have been the Wintergarten. Immediately, HMS Offa opened fire with the starboard Oerlikons, the main armament and pom-poms being unable to depress enough to gain aim, and several hits were observed against the conning tower. At 0316, when the U-boat began a crash dive, McCoy ordered the wheel put hard-a-starboard to ram. The ship’s bows began the turn, but the U-boat’s dive, at about eight knots, was very steep and the conning tower was observed to be disappearing safely under the ship about level with the bridge. McCoy himself could see the hull of the U-boat under the surface as HMS Offa passed over and ahead. In his after-action report he described what happened next:

“Then I gave the order to fire [D/Cs]. This order most unfortunately miscarried. During the hunt I had twice given orders for the throwers:—in the first instance: “Ready Port,” and in the second instance: “Ready Starboard”; but at the moment when I put the helm over it became obvious that the starboard throwers only would be required and I gave the order “Ready Starboard.” These were fired correctly but when I followed this up with an order to “fire everything” the man at the pump lever to the traps was so obsessed with the order to fire the starboard throwers only that he failed to fire the traps and so the barrage from the traps, which would have been laid down in a curve over the U-boat, was not dropped and certain destruction was not obtained.”

Though the failure to fire was “lamentable,” as McCoy stated elsewhere, and whereas Admiral Horton himself lamented later “the failure of a rating to carry out an order at the critical moment,” the CinCWA judged McCoy to have conducted this operation “in a very able manner.” And while neither man would know it at the time, the detonations of the starboard throwers were sufficient to cause slight damage to the U-boat involved, which, it turned out in a recent reassessment, was U—223 (Oblt.z.S. Karljüng Wächter). That boat, which had a bit of ginger taken out of her this time, would be rammed later, on 12 May, but survive again, until finally succumbing to four British warships on 30 March 1944.

At 2240 on the 5th, HMS Sunflower was manning station “M” on the port bow when Lt.-Cmdr. Plomer’s radar received a pulse echo from 4,300 yards. HMS Sunflower altered course and closed the contact at 14 knots. The U-boat dived and asdic pursued it. At 200 yards from the contact the bearing began moving from left to right. Following, the corvette dropped six and fired four D/Cs in what Plomer called “our best D/C attack—almost exercise conditions.” Just before the D/Cs went overside, at 2251, HMS Sunflower picked up a second radar contact at 3,400 yards, and Plomer decided to pursue that one at once, in order, we may conjecture, to keep the U-boats off their stride. As he did so, asdic told him that a torpedo was approaching from red (port) 20°. He watched as it passed down the corvette’s port side. Immediately, radar picked up yet another contact at 2,800 yards, but now Plomer decided to pursue the U-boat that had attacked him, and at 2258 he sighted it close ahead.

HMS Sunflowers deck gun opened fire, but on the third round the cartridge jammed in the breach. Without an operative main armament, Plomer altered course to starboard at 2305 in an attempt to drive underwater his radar contact of fourteen minutes before. Two minutes later, asdic reported incoming torpedoes—a “full salvo”—from the boat he had just been pursuing. Putting helm hard-a-port, then point back, HMS Sunflower managed to be 30° off pointing when the salvo arrived down the port side. Plomer signaled HMS Tay at 2312: “Have broken off chase, fired two H.E.s [high explosive rounds], could not gain.” Two minutes later, however, his gun reported clear, and Plomer decided he was back in the game. For the next three and a half hours he chased five contacts, firing Hedgehogs at one and a five-charge D/C pattern at another, but all without result. The NHB/MOD reassessment believes it possible that these attacks were delivered against the same target, U-954 (Kptlt. Odo Loewe).

At 0443, while back on station “N,” 6o° on the convoy’s port bow, HMS Sunflower received a firm asdic contact at 1,200 yards. The U-boat, it turned out, was in the act of surfacing. Plomer closed at 14 knots in 300 yards visibility and found the German fully surfaced broad on the port beam, on a converging course. He switched on his searchlight, and the U-boat immediately commenced a dive. Plomer then ordered hard to port rudder and double emergency full ahead. In the last seconds before impact hard to starboard was ordered as a course correction, and in Plomer’s description, the corvette rammed the U-boat between its conning tower and stern, riding over the U-boat’s casing like an icebreaker over ice. As she passed, Sunflower dropped two D/Cs set to shallow; a moment before they detonated, the corvette’s crew heard another distinct “heavy explosion.”

Plomer was persuaded that the U-boat had broken in two, since his two asdic domes underside were undamaged. His last sight of the U-boat, he said, was of her stern projected about 8 feet above the surface at an angle of 45°. All guns that could bear were brought into action. With no further contact showing on asdic, and convinced that the U-boat had sunk, Plomer set course to rejoin the convoy. Among the spectators of this encounter were the Master and sixty-five other survivors of M.V. Dolius, who had been picked up by HMS Sunflower the day before. Said Captain Cheetham: “I and my crew thoroughly enjoyed ourselves.” While the corvette’s asdic was still fully operative, she soon discovered defects from the ramming, including leakage in the fore-peak. Furthermore, she signaled Tay by R/T: “My steering is erratic as gyro is out of action and magnetic compass shaken up a bit. Please give me a wide berth. 0505.”

In his after-action report Plomer pronounced the engagement a “kill.” Similarly, Captain J. M. Rowland, R.N., Captain (D) Newfoundland, called it a “certainty”. In London the Admiralty was less convinced. Complaining that Plomer’s report contained no details about exterior damage inflicted on the corvette, or about any wreckage, oil, or survivors seen in the water after the ramming, the U-Boat Assessment Committee expressed doubt that the U-boat had been effectively rammed, much less cut in half. It was much more probable, the Committee argued, “that after a glancing blow the U-boat slid off.” And it gave no credence to the suggestion of an internal explosion. As for the two depth charges, it was unlikely that they were in the lethal range. The assessment, given on 21 June, therefore, was: “Probably slightly damaged.” But the Committee’s finding may have been disingenuous, for one of its members always consulted Rodger Winn in the OIC Tracking Room for an opinion. While Winn never transmitted raw Enigma to the Committee, or even divulged to it explicit information drawn from Enigma, it is known that both before and on the date of the Committee’s deliberations, Winn held in hand a decrypt of a transmission from U-533 (Oblt.z.S. Helmut Hennig) to BdU, intercepted at 1137 on 6 May and decrypted at 1917 on 9 May:

RAMMED ASTERN BY A DESTROYER [SIC] THAT APPEARED OUT OF THE FOG, LOCATING ME BY SEARCHLIGHT. DEPTH CHARGES. AM MOVING OFF TO REPAIR. BOAT WILL BE READY AGAIN IN 18 HOURS. QU AJ 8683

At 1000, U-533 surfaced and made off to the east on course 90° to undertake repairs. These completed by 1800, she continued east, then northeast on 7 May to join sixteen other former Fink boats in forming Group Elbe (after the river). That group and a ten-boat Group Rhein (after the river), organized from former Amsel III and IV boats, were to occupy a 550-mile-long patrol line across the expected courses of two eastbound convoys, HX.237 and SC.129 (see chapter 10). The wounded U-533 successfully took her place in line.

At daybreak on the 6th, four of the five ships making up the First Escort (Support) Group (EGI), the sloop HMS Pelican and frigates HMS Wear, HMS Jed, and HMS Spey—the slower cutter HMS Sennen was on a different course to support Pink—were closing on ONS.5 from the southwest. In line abreast, four miles apart, their bows cleaving the swells and fog, the warships rode down spur and rein, on 030° at 16 knots, like a seaborne Seventh Cavalry. Numerous R/T signals between busy B7 and EG3 escorts helped the support group home in on the convoy by HF/DF, and at 0550, Wear reported the convoy bearing 330°, 8 miles. The group was now inside the Fink concentration. Senior Officer, in HMS Pelican, was Commander Godfrey N. Brewer, R.N., who, after a year at sea in 1939–1940, had been posted to the Trade Division of the Admiralty as Convoy Planning Officer, where he had the advantage of seeing the “big picture” of convoy warfare. “Escaping back to sea,” as he put it, in spring 1942, he returned to Atlantic escort duty with EGI.

At 0552, HMS Pelican obtained a small radar contact bearing 040°, range 5,300 yards. When it was classified as “submarine,” Brewer closed the contact, keeping it about 10° on the starboard bow to avoid the ship’s “blind spot.” From the bearing and rate of change in the range, it soon became apparent that the U-boat was on a heading reciprocal to that of the group. Brewer thought that it either had just been driven off after attempting an attack or was proceeding ahead to take up a daylight submerged bow ahead attack position. When the range was 3,000 yards at 0557, HMS Pelican began hearing faint hydrophone effect on a bearing of 160°, and several minutes later, when the range had been closed to 500 yards, lookouts sighted a bow wake on the starboard bow.

At 0607, range 300, the U-boat itself became visible on the foggy surface, steering 180°, doing about nine knots, as Brewer judged from the relative speed of approach. It was, he said, “a normal 570 ton type [VIIC] painted a dark colour.” When about 100 yards distant, and fine on the port bow, the U-boat crash-dived, turning to port as she sank. Pelican’s A and B guns and the port Oerlikon opened fire. Brewer swung to port under full rudder and placed his bows just inside the conning tower swirl. As he passed, he fired a ten-pattern set to 50 and 150 feet. After the explosions, a “very weak and hard to hold” echo was regained, and about a minute later, the Officer in Charge and most of the D/C crew sighted at the explosion area what they described as “two thin founts of water, resembling shell splashes.” Brewer came around for a second attack, and during the run-in, with the contact moving very slowly right, hydrophone effect detected various strange noises resembling an Echo Sounder set being switched on and off. This time nine charges set to 150 and 300 feet left the throwers and rails, after which there was no further contact.

A minute and a half later, HMS Pelican heard three “small sharp” explosions together with the same switching noises as before; and nine minutes after that, HMS Pelican heard two more explosions, the second of which shook the ship. None of the explosions, Brewer remarked, sounded like the detonation of a torpedo or a depth charge. Though afterwards HMS Pelican carried out an Observant around the attack position, no wreckage, oil, or survivors were sighted. But based on circumstantial evidence, Brewer’s “considered opinion” was that the U-boat was probably sunk. On 28 June the U-Boat Assessment Committee, basing its conclusion largely on tracking evidence and on the fact that there were no further W/T transmissions from this boat (as Donitz and Godt noticed, too, as early as the end of the day, 6 May), agreed with Brewer’s opinion. So does the recent NHB/MOD reassessment. The victim was U—438 (Heinsohn), which had been damaged by Canso PBY Catalina flying boat “A” E of 5 Squadron from Gander on the afternoon of the 4th. In good cavalryman fashion, Brewer stated: “This was a good example of a support group arriving at just the right moment to achieve complete suprise."

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Brewer might have swept about further, seeking other boats to rend and tear, but for the fact that ONS.5 badly needed reinforcement of the close screen, and defending convoys still had the edge over hunting Uboats in escort doctrine. With EGI’s arrival, McCoy on HMS Offa decided that he ought to escort the other remaining EG3 destroyer, HMS Oribi, out of the endangered area as quickly as possible and see her to safety at St. John’s: by daybreak, as a result of her ramming action, HMS Oribi’s forepeak and provision room were both flooded. Accordingly, HMS Offa detached at 0809, ordering HMS Oribi to join and adding a personal message to Ingram: “I should say you have done bloody well during the past 24 hours.” The two destroyers made port at 1215 on 8 May.

The B7 flotilla left behind was sore beset by battle fatigue and fuel depletion from the night’s running fight; furthermore, with HMS Sunflower licking wounds from her ramming of U-533, HMS Snowflake lacking D/Cs, and HMS Tay with no asdic, HMS Vidette and HMS Loosestrife were the only effective ships on the screen of the main body. So HMS Pelican and HMS Jed took up stations ahead and Brewer detailed HMS Spey and HMS Wear to sweep twenty miles astern. Much later, at 2300, slow-gaited Sennen would join HMS Pink with her four merchant vessels in company. On her course toward that rendezvous, which took her to the west of the main body, HMS Sennen acquired two radar contacts, five hours apart, at 0740 and at 1244, which enabled the 1,546-ton ex-U.S.C.G.C. Champlain and her captain, Lt.-Cmdr. F. H. Thornton, R.N.R., to participate in the final moments of the battle. The first contact was obtained bearing 289°, range 4,000, and four minutes later HMS Sennen sighted the U-boat diving at 2,500 yards. When asdic contact was gained three and a half minutes later, Thornton commenced an attack with a ten-pattern set to 150 and 300 feet. Following the attack, which was made at 0753, Sennen regained and lost contact three times, eventually giving up on it and resuming course. Thornton judged that the attack was unsuccessful: “Pattern fired late due to poor recorder trace, and probably too shallow.” The NHB/MOD reassessment agrees and identifies the cutter’s contact as U-650 (v. Witzendorff), which had been the shadower in Group Star.

HMS Sennen ‘s second radar echo at 1244 led to a more persistent effort, as the feisty cutter made no fewer than five separate attacks, two by Hedgehog, and three by D/C, at 1255,1342,1405,1436, and 1522. As in the earlier incident, the U-boat was sighted in the act of diving, this time at 4,000 yards. By asdic recorder Thornton first fired Hedgehog, with no explosions; then attacked with D/Cs set to 150 and 385 feet; then fired Hedgehog, with, again, no explosions; then made two successive D/C attacks, the first of ten set to 150 and 300 feet, the second of five set to 550. With no surface evidence to confirm otherwise, Thornton concluded that the U-boat was “probably not more than badly shaken.” The NHB/MOD reassessment concludes that the U-boat received “minor damage,” and identifies it as U-575 (Heydemann).20 Thornton then proceeded from the area on his original course in order to conserve D/Cs and Hedgehog ammunition, since he had learned that Pink was short of both, and “there were still a large number of submarines in the vicinity.… ”

While trawling astern of the main body, HMS Spey obtained a radar contact on the port bow, range 5,200 yards, closing rapidly. The time was 0940. Commander L. G. BoysSmith, R.N.R., rang up full speed and altered toward the contact, which was soon classified as “submarine.” At 900 yards the U-boat was sighted in the morning’s thick mist, crossing from starboard to port at an estimated 12 knots. To BoysSmith the boat resembled the large “Dessie” Class Italian submarine. He ordered the frigate’s four-inch to open fire and altered to port, hoping to ram. The U-boat dived at 400 yards, but not before the gun crew got two definite hits, one on the conning tower base and one on the hull, and a third possible. The second hit threw up a heavy shower of debris. Pom-pom and Oerlikon fire also raked the tower as it slid beneath the waves.

HMS Spey quickly established asdic contact and BoysSmith ordered a ten-pattern D/C attack, with lights set to 50 and heavies to 140 feet, carried out by eye over the clearly visible diving swirl and wake; the eyeball order was confirmed by recorder trace. When contact was regained on the port quarter after the attack explosions, HMS Spey set up a Hedgehog attack. Asdic showed that the U-boat had turned at about two knots but contact was lost at 500 yards, indicating that the target had gone very deep by the time the H.H. was fired. There were no explosions. With a contact astern at 700 yards, HMS Spey launched a third attack, employing ten D/Cs set to 500 and 550 feet, after which contact was not regained.

At this point, HMS Wear joined in the sweep, and a less than confident contact was obtained, held to 400 yards. Ten charges set to 150 and 385 feet were delivered by Spey, after which all contact was lost. In Boys-Smith’s opinion, his four attacks were “inconclusive.” The U-Boat Assessment Committee decided: “Probably slightly damaged.” The NHB/MOD reassessment is that U-634 (Oblt.z.S. Eberhard Dahlhaus) suffered damage from four-inch gunfire but none from D/Cs. Dahlhaus’s KTB reveals that he was wounded in the neck by a splinter. His F.T. to BdU reads: a full hit by destroyer artillery after surfacing. port air supply trunk bridge torn away. heavy d/c and radar pursuit. BoysSmith’s target was not a large boat, after all, but a standard VIIC, with 114 more days of life.

It was after HMS Spey’s attack that the battle’s fever broke. At 1140, having sensed the dimensions of what Germans later would call die Katastrophe am ONS.3 (Catastrophe of Convoy ONS 3) , Dönitz and Godt ordered the Fink boats to break off operations. Amsel I and II boats were to head for qu BC 33 (5o°33’N, 39°15’W) and the remainder were to move off to the east, some for replenishment of fuel and supplies from U—461 in AK 8769.23 The order was a recognition that Dönitz and Godt had lost what could have been a drawn battle had they discontinued at dusk on the 5th. In a veiled concession that they had instead reached a night too far, the two German Admirals signaled their Commanders:

THIS CONVOY BATTLE HAS ONCE AGAIN PROVED THAT CONDITIONS ON A CONVOY ARE ALWAYS MOST FAVORABLE AT THE BEGINNING. HE WHO EXPLOITS THE MOMENT OF SURPRISE ON THE FIRST NIGHT, AND PRESSES HOME THE ATTACK BY ALL MEANS IN HIS POWER, HE IS THE MAN WHO IS SUCCESSFUL. AFTER THE FIRST BLOW IT BECOMES HARDER AND HARDER. IN ADDITION THERE IS THE UNCERTAINTY OF THE WEATHER, AS ON THIS OCCASION, WHERE THE FOG RUINED THE GREAT OPPORTUNITIES ON THE SECOND NIGHT. WE APPRECIATE YOUR HARD STRUGGLE, ESPECIALLY ON THE SECOND NIGHT.

In their wash-up on “Convoy No. 36” at the close of 6 May, Dönitz and Godt concluded that six boats had been lost in the Fink campaign—U-638, U-192, U-123, U-331, U-630, and U-438. “If none of these boats report later, this loss of 6 boats is very high and grave considering the short duration of the attack. The blame can be laid mainly on the foggy period that began at 2100 [GST] on the 5th May.” If the fog had held off for six hours, they contended, the U-boats would have had “a really good bag that night,” but “the fog ruined everything.” They did not concede that staff meteorologists, from a year and a half of U-boat experience in the western Atlantic, not to mention book knowledge, should have known that where the Gulf Stream met the Labrador Current, causing warm water to mix with cold air, there was almost always opaque vapor, especially in the spring, and that the Grand Banks were renowned for their milk-white air. Nor did they concede that the same fog that blinded the U-boats made air cover from Newfoundland impossible for the enemy. Curiously, the Naval Staff at Eberswalde, not many kilometers from BdU, did anticipate the whiteout: “As the enemy is today entering the heavily fog-bound area, it is to be expected that only a small portion of the boats will be able to maintain contact.” This was on the 5th. Whether there was communication with BdU on the point is not disclosed in the extant records.

The U-boat loss count would be even higher, by one, on 23 May, when BdU acknowledged that U-209, damaged by Canso “A” W 5 Squadron on 5 May, had foundered with all hands (probably on 7 May in the vicinity of 52°N, 38°W) during her desperate attempt to make base. And one could add as well the loss of U-710, sunk by Fortress “D” 206 Squadron on 24 April during the first stage of the battle. The exchange rate of U-boats lost for merchant ships sunk in the two stages was alarmingly high, even given the inflated figures of ships sunk that were transmitted by Commanders to Berlin. The actual number of merchantmen lost to U-boats from ONS.5, beginning with McKeesport and ending with Bonde, was thirteen. The number reported to Berlin was nineteen merchantmen torpedoed and sixteen sunk (90,500 GRT), including Hasenschar’s erroneous count of two definites, including a corvette, plus two probables, which led Donitz and Godt to add to their “hard struggle” message, cited above: hasenschar is champion shot. That honor should have gone to Jessen (U—266), with three definites.

In either event, such high losses of one U-boat (using the low figure of six boats) for every 2.16 (using the actual figure of thirteen merchantmen) or 2.66 (using the claimed figure of sixteen) ships sunk was an attrition rate that could not be borne, and as Donitz stated later, “I regarded this convoy battle as a defeat.” More irreplaceable than the boats, and more critical a loss at this period of the war—one remembers the dangerously declining numbers of trained RAF pilots during the Battle of Britain—was the death toll of U-boat ranks and ratings: a total of 364 human casualties.

Also telling, apart from the number of U-boats sunk, was the number of boats damaged by escort action: Seven boats were so severely impaired they were forced back to base: U-386, U—528, U—332 (in the first stage of the battle, 28 April-1 May), U-648, U-732, U-358, and U-270 (in the second stage, 4–6 May). As noted earlier, boats forced home were the tactical equivalents of kills in a convoy battle. Eleven other boats were roughly handled, suffering heavy to light damage: U-413, U-314, U-648, U-438, U-226, U-223, U-533, U-634, U-266, U—267, and U-575. These boats were removed from the scene for a time, either long or short, while they undertook repairs, and thus were not available during those intervals for operations. (Since Professor Blackett considered four boats damaged to be the equivalent of one boat sunk, by that measure 4.5 boats could be added to the tally of those sunk.) Also notable in the defense of ONS.5 were the twenty-odd occasions when U-boats were driven off or forced to dive; submerged, it bears repeating, they were greatly retarded in their ability to make nighttime attacks. And mention should be made of several boats, such as U-552 (Kptlt. Klaus Popp), that were forced to retire by reason of fuel depletion.

Finally, the records disclose a failing that was endemic to the U-boats in this period and for some time prior: most were not pressing their strength in numbers and most were not taking their shots. Although Fink boats made approximately forty attacks, the vaunted BdU wireless control system seems never to have directed more than fifteen boats at a time into close contact with the convoy, the usual number brought to bear being no higher than nine. In the late forenoon of the 5th, BdU had expostulated: there are forty of you. And the boats in contact correctly reported the convoy’s position and base course all through the battle, as Enigma intercepts disclose. What was the problem? Was it perhaps the low level of command experience, previously noted, that inhibited the effective maneuver and attack of certain boats? Or did low fuel levels in many boats perhaps induce a caution that led those Commanders “to lose the name of action?” Or did the aggressive behavior of the escort screen, which punched as often as it counterpunched, simply succeed tactically in holding the majority of boats at bay? The textual record would support all three possibilities.

In W/T transmissions to Berlin on 5/6/7 May, a significant percentage of the boats reported large numbers of unexpended torpedoes. It is not unusual to read, for example, in the traffic from U-223 and U-378 on 5 May: 12 e torpedoes, 2 a torpedoes, their full complement for a VIIC boat; or in that from U-514 on 6 May: all torpedoes, or in that from U—231 on 6 May: all eels. (This was a longtime besetting weakness of the U-boat force, of which only a little more than 50 percent of boats actually engaged in combat operations sank or damaged an Allied vessel during the war.) That so large a concentration of boats, deployed in such favorable position, should have come up short in torpedo launches must have cast a pall of doubt over BdU planning for future operations.

Fog was not alone to blame for the defeat. Dönitz and Godt stated, “The operation against Convoy No. 36 also had to be broken off because of enemy radar.” It was obvious that in low-visibility conditions the convoy escorts had been able to readily locate the positions of surfaced U-boats, and without the boats learning of their exposure by means of the standard Metox search receivers. The surface escorts, and aircraft, too, it was reasoned, must be equipped with some new kind of detection equipment. Finding an answer to this problem was of “decisive importance” for submarine warfare. “To sum up,” they wrote on 6 May:

“Radar location by air and naval forces not only renders the actual attack by individual boats most difficult, but also provides the enemy with a means of fixing the stations manned by the submarines and of avoiding them, and he obviously makes good use of this method. Radar location is thus robbing the submarine of her most important characteristic—ability to remain undetected. All responsible departments are working at high pressure on the problem of again providing the submarine with gear capable of establishing whether the enemy is using radar; they are also concentrating on camouflage for the submarine against [radar] location, which must be considered the ultimate goal.”

Dönitz’s son-in-law Günter Hessler, who served on Godt’s operations staff, wrote after the war that staff thinking at the time was that the Allies were using either a radar wavelength beyond the capacity of the Metox to detect (which was correct) or a nonradar device such as infrared rays. He expressed the dismay of the staff that in the just-completed operation, “surface escorts alone had sufficed to inflict grave losses on an exceptionally strong concentration of attackers.” Where the Allies spoke of the “U-boat menace,” the Germans now spoke of the “radar menace.” Unless that menace could be quickly and effectively countered, Hessler said, the position of the U-Bootwaffe would become “desperate.”

In his Memoirs, Dönitz, too, stated that in further convoy operations conducted in poor-visibility conditions, which were a common occurrence in the North Atlantic, the U-boats would be helpless. The Allies’ radar advances, furthermore, would enable convoys to take effective evasive action. And radar was not the only technical problem the Germans had to face at this juncture. Hessler informs us that there was consternation expressed after Convoy No. 36 about the fact that British warships were now equipped with powerful new deep-plunging D/Cs as well as with Hedgehogs, about which BdU had learned earlier from decryption, agents, and practical experience. The panoply of weapons arrayed against the U-boats was increasingly sophisticated and effective, particularly since new tactical refinements to “under-water location,” or asdic, had made possible accurate depth charge pursuits on days and at times “when there was fog.”

In their 6 May appreciation Dönitz and Godt also took serious notice of the danger posed to U-boat patrol lines by Allied air escorts, which had “always forced our submarines to lag hopelessly behind” convoys and had prevented them from scoring hits, “especially when naval [surface] and air escorts cooperated efficiently.” They predicted correctly that “the only remaining [air] gaps will be closed within a reasonable length of time by land-based planes, or at any rate by using auxiliary aircraft carriers.” Finally, the Dönitz/Godt wash-up deplored the fact that except for the Pi 2 magnetic influence pistol and a few other minor innovations, “as yet we possess no really effective weapon.” This was a stunning concession. They concluded: “The submarine’s struggle is now harder than ever, but all departments are working full out to assist the boats in their task and to equip them with better weapons.”

They gave no hint, at least here, that they feared insecure W/T communications; although, in fact, Allied cryptographic sources played no role in the defense against Fink, and most naval Enigma from 5/6 May was not decrypted until the 9th. They made no mention, either, of HF/DF, which, despite ample cryptographic and operational evidence, both BdU and Naval Intelligence analysts continued to believe was limited to shore-based installations. Refusal to admit the possibility of shipand aircraft-borne HF/DF had yielded substantial tactical advantage to the Allies, and would continue to do so.

Nor did they mention that their long-established principle of concentrating the largest possible number of boats on an individual convoy—in this case nearly one-half of the whole Atlantic force—rather than make fewer attacks on a greater number of contacts had let six other convoys pass unmolested, and had immobilized the attacking force for a week afterward, during which time boats had to be refueled or replaced.Nor was there any mention in the BdU war diary, or in Hessler’s recollections of the BdU mind in early May, of a decline in crew morale and confidence resulting from recent reversals. As shown in the prologue, this was a recurring subject of speculation in the OIC Tracking Room in London, where, at least since 19 April, Rodger Winn had observed in W/T traffic what he thought was an increasing anxiety among Commanders.

So far, by the close of 6 May, the beleaguered circle held. Surviving U-boats in the mid-Atlantic regrouped to fight another day, and another night. As the deadly duel continued, there was no question of the fighting spirit exhibited on either side.

While they had no way of knowing about BdU’s order of 1140 halting offensive action, no doubt the B7 and EGi escorts were aware during the late forenoon and early afternoon hours of the 6th that an eerie peace had drifted out from the enveloping fog. There had been no known German torpedo attack against a merchant ship or escort since 0527, when U-192 (Happe) launched a brace of stern tube eels at HMS Loosestrife. The U-boats were still about, as HMS Pelican, HMS Sennen, and HMS Spey had proved, detecting three on the surface between 0551 and 1244, but there had been no observations of periscope wakes or torpedo tracks, which one might have expected on the daylit sea, even in its gauzy cover. Most of the boats appeared to be lying doggo below, outside of asdic range. By an ironic twist, which most hands probably noted, during the preceding night it was the U-boats that had become the quarry, and the escorts the hunter. Perhaps no one was more elated to receive that understanding than Commodore Brook, on Rena, who entered a condensed account of “this big Convoy Battle” in his final report, and set down the score as he learned it from HMS Tay.

What was left to do, besides mopping up attacks by HMS Sennen at 1244 and by HMS Jed, which would make the final D/C attack on a probable U-boat contact at 2357 that night, was the collecting of merchant ships that had become scattered in the black and the fog, and the refueling of HMS Vidette from British Lady beginning at 1130.37 That completed, the convoy proceeded without incident toward the Western Ocean Meeting Point (WESTOMP) at 48°11‘N, 45°39’W, east of St. John’s, where Canadian warships out of Newfoundland were scheduled to relieve the ocean escort. At 1500, Sherwood’s Mid-Ocean Escort Group B7 and Brewer’s First Support Group were joined by the Canadian Western Local Escort Force (WLEF), W-4. They were four corvettes, by name: HMCS. Barrie (SO), HMCS Galt, HMCS Buctouche, and HMCS Cowichan. All the assembled forces together with the convoy columns continued toward WESTOMP, the Navy and Merchant Navy crews of B7 and ONS.5 now having every reason to sense the approaching end of a near three-week ordeal, during which they reached and surpassed the human equivalent of PLE. Their stained, worn ships, having survived both the lash of a stern, impartial sea and the bitterest convoy battle of two world wars, rose and dipped with a sober gravity.

Behind ehind their weary screws flowed runnels of gray and white Grand Banks wash. Beneath their keels the Atlantic shoaled on the continental shelf. The long billows of the central ocean gave way to a shorter and choppy surface, while on either beam squadrons of gulls parked on the water to announce the impending shore. What was best, we may believe, the scent of victory was in the air. No one yet could let down his guard, and none could forget merchant mariners left behind in the deep transepts of the cathedral sea, but a lightened mood understandably took hold among all ranks and ratings, whether under the white ensign or the red duster. There was occasion now for the concertina, the George Formby song, dominoes, “uckers” (ludo), or cribbage. And a long unburdening sigh.

Game, set, and match: U.K.

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That night, at 2357, HMS Pelican received a signal from CinCWA directing her, HMS Wear, and HMS Jed to part company from the convoy at daylight on the 7th, if convoy considered no longer threatened, and to proceed at economical speed astern of the convoy to search for torpedoed ships that might still be afloat. They would find no derelicts, but on the forenoon of the 8th, in thick fog, they sighted wreckage and empty lifeboats. After several course changes to support convoys ON.181 and ONS.6, as directed by CinCWA, the three support ship vessels returned through heavy broken pack ice to St. John’s, arriving on the 12th.39 At 1650 on the 7th, on orders from HMS Tay, HMS Vidette and HMS Loosestrife disengaged from the convoy to escort three vessels to St. John’s: British Lady, Empire Gazelle, and Berkel (the last of which had survived the collision with Bornholm on 25 April). They arrived on the forenoon of the 9th. The remaining ships of B7, HMS Tay, HMS Snowflake, and HMS Sunflower, parted company for St. John’s on the same day, arriving on the 8th. HMS Pink with her straggler party made the same port on the 9th. As for the main body of ONS.5, destined for Halifax, Boston, and New York, Commodore Brook’s final report read simply (in local time):

May 12th0520 Detached NY and Boston groups with 3 Corvettes escorting.
1100 Formed single line ahead.
1200 Proceeding up Swept Channel Halifax.
1300 Approaching Pilot Station. Convoy completed.

It was twenty days since the departure from Oversay. A few individual stragglers made port in the days that followed.

On shore, the By, EG3, and First Support Group Captains typed up their proceedings and after-action reports. Several of them offered, in addition, their reflections on such topics as convoy routes, the performance of personnel, the endurance of escort vessels, the usefulness of weaponiy and equipment, and U-boat tactics. A preliminary summary of certain of these comments was prepared on 9 May by Flag Officer Newfoundland Force (Commodore H. E. Reid, R.C.N.) for ciphered transmission to Commander-in-Chief North West Atlantic (CinCNA), Rear Admiral L. W. Murray, R.C.N., in Halifax. The summary began with the observation that the convoy battle had been divided into two periods, 28 April to 1 May and 4 May to 6 May, with a three-day gale in between. After noting that scare tactics based on HF/DF bearings had proved successful, the summary continued:

“U-boats were attacking by night in pairs and threes. Possibly 1 day attack delivered by pair. No new tactics in night attacks. By day, U-boats approached from ahead of centre of convoy and fired from between the columns. U-boats were using 2 different H/F frequencies simultaneously during the night of 4th May. Possibly 2 different packs attacked. A.C.I. [Atlantic Convoy Instructions] diagrams and orders used throughout. Experience shows that at night 6 ships is minimum number on [Type] 271 [radar] close screen unless weather permits 1 side of screen to be left unprotected and that 271 fitted ships of Support Group should be stationed at least 8 miles clear of convoy. Cooperation between Escort and Support Group excellent. Little air cover available due to weather which also prevented fuelling of escorts. Tanker “British Lady” did not carry enough fuel. Rescue trawlers proved their use. It is strongly suggested that convoy was routed too far north into ice and bad weather. Only on 1 night after gale had scattered convoy and in rough sea did U-boats gain upper hand. It is thought likely that day attacks will become more and night attacks less frequent as result of this battle.”

Among the individual ship reports, HMS Tay commented: “All ships worked hard, capably, and with intelligence and considerable humour, and the situation was always well in hand.” And again: “All ships showed dash and initiative. No ship required to be told what to do and signals were distinguished both by their brevity and their wit.” Sunflower stated that his asdic team were “most keen and efficient at all times,” and that his D/C team were a close second. The radar operators, with one exception, had no prior sea experience; they compensated for that somewhat by their zeal. The Chief Bos’n’s mate and the Coxs’n had shown exceptional leadership in keeping ship’s company, many of whom were at sea for the first time, up to the best service traditions.

HMS Snowflake observed that the four-inch H.E. was effective in forcing a U-boat to dive when radar reported a boat dead ahead and the gun was trained with sights set to zero: “This obviated the necessity of a long chase.” (The corvette, it is remembered, was slower than the U-boat on the surface.) During a concentrated attack by U-boats, Snowflake recommended, priority should be given to the speed rather than to the accuracy of the counterattack, so that the escort could retake position on the screen in the shortest possible time.

Destroyers HMS Penn and HMS Panther of EG3, which had been with the convoy for fewer than two days (2–4 May) because of fuel depletion, weighed in with comments about their short-legged craft, HMS Penn suggesting that support group operations should be so arranged that destroyers heavy on oil fuel were not sent long distances from base, “as their first need on meeting a convoy is a large amount of fuel,” and bad weather often made refueling impossible. HMS Panther suggested “that Sloops and Frigates (who are not constantly faced with fuel problem) ought to make up support groups, and that destroyers should always form part of a definite escort group”—a suggestion fully concurred with by CinCNA, Rear Admiral Murray at Halifax.46 For his part, Convoy Commodore Brook praised “the splendid work throughout on part of Escorts, not forgetting (SO) HMS ‘DUNCAN’ who unfortunately had to leave Convoy short of fuel just before Convoy Battle materialized.” Senior Officer Peter Gretton was all too conscious of his misfortune as he talked in St. John’s with the B7 captains and read their reports. That misfortune being that he had missed out on the events of 5/6 May, which were, he said, “probably the most stirring of convoy history.” By a combination of “skill, luck, initiative, and sheer guts,” his B7 group, helped by EG3 and First Support Group, had brought off one of the epic victories in the story of sea warfare. Twenty-one years later he would still be tending to his “wounded vanity,” writing: “I shall never cease to regret that I did not risk the weather and stay with them until the end.… The weather did improve and I would probably have been able to fuel.… I had missed the ‘golden moment’ which comes but once in a lifetime.”

Yet Gretton’s wounded vanity should have been assuaged by the commendations that came to him on every side for having trained so capable a force as B7, which, as HMS Tay’s report noted, needed no further instructions on what to do when the hour of maximum danger arrived. Rear Admiral Murray was unstinting in his praise: “The absence of the Senior Officer of By on the big night, while unfortunate and inevitable, nonetheless speaks volumes for the training he is responsible for in this outstanding Group.” Admiral Horton himself commented that it was “a credit to the training of the group that in his [Gretton’s] absence it was so ably led by his second in command, Lt.-Cmdr. R.E. Sherwood, R.N.R., HMS TAY.”

Gretton had been the first to laud Sherwood’s performance. He had been in Tay with Sherwood during the battle for HX.231, and “I knew that he could compete.” In his own analysis of the 5/6 May engagement, produced shortly after the arrival of the B7 Captains at St. John’s, Gretton wrote that, “Lieutenant-Commander Sherwood of HMS TAY handled a very dangerous situation with ability and coolness. I consider he did exceptionally well, being ably backed up by the group.” It is worth adding that the two-and-a-half-ringed reservist won his victory in the presence of two RN Captains.

Convoy ONS.5

Route and engagements of ONS.5 , the decisive turning point convoy battle of Battle of Atlantic

With the after-action reports in hand, Gretton offered further comments on the two stages of the battle: He agreed with his Captains that the convoy had been routed too far to the north, where ice and gales retarded forward progress, prevented fueling, and scattered ships. (This view subsequently was endorsed by Rear Admiral Murray. Recognizing that the far northern route had been selected for evasive purposes, Murray concluded, “It is very much doubted if the game is worth the candle.”) Since near Greenland W/T ship-to-shore communication was impossible on any frequency, and the U-boats, which had superior wireless gear, were having the same trouble, the Admiralty should not assume, said Gretton, that a convoy in those latitudes was not being shadowed because of an absence of signals. EG3 was a model of cooperation and assistance, and the presence of HMS Offa and HMS Oribi on 5/6 May made a significant difference in the battle. Aircraft, particularly the Liberators, which flew to the extreme limit of their endurance in appalling weather, deserved great credit for their coverage, as did the RCAF Canso PBY Catalinas from Newfoundland that attacked two U-boats on the 4th, though fog prevented further air assistance from that quarter.

Crediting her as exhibiting “the most outstanding performance” in his B7 group, Gretton singled out HMS Snowflake for “carrying out at least 12 attacks and finally bagging a U-boat"; though in fact HMS Snowflake, which made seven attacks during the voyage, did not actually sink a boat, and the palm might more fittingly have been awarded to HMS Vidette, which sank two. His only criticism was reserved for HMS Pink, which, he said, made “an incorrect decision” in leaving his straggler station to go after a U-boat (U-358) on the 5th, but, he conceded, “I would have made it myself.” In his operation against ONS.5, the enemy had been “dealt a blow that may have far-reaching results on their future tactics and which must inevitably increase the proportion of day to night attacks.”

In what was perhaps Gretton’s most provocative observation—one that would draw comment from the demanding, some would say irascible, Captain G. W. G. “Shrimp” Simpson, R.N., Commodore (D) Western Approaches in Londonderry—he stated that the just-completed convoy battle proved, as had HX.231 before it, that in favorable seas, an efficient close screen in correct station could alone prevent surfaced night attacks on a convoy. Simpson’s read on Gretton’s confidence in the close screen was more differentiated and searching:

“A point which is brought out is that when a close R.D.F. [radar] ring of well-trained escorts is round the convoy they can defeat the U-boat on practically every occasion, as was proved by the action on the night of 28/29 April, when six attacks were beaten off without loss. It is noted that losses to the convoy did not occur until the close screen had been reduced to five and then to four escorts. It is considered that it is essential for the safety of a convoy that there should be eight escorts stationed on the close screen. On the night of 4th/5th May, five merchant vessels were torpedoed after the close screen had been reduced to five escorts, and it is considered that if Offa and Oribi, who were on the extended screen, had been brought in to support the close screen, as was done the following night, better protection for the convoy would certainly have resulted.… Offa and Oribi, disposed singly on the outer screen, could not contribute much to the safety of the convoy and were themselves in considerable danger of being torpedoed.”

Admiral Horton concurred in this criticism, noting only that a close escort of eight was the minimum required “at night under normal circumstances.” Where Simpson went on to criticize Tay for taking the ahead station on the screen when her asdics were out of action, Horton thought that under the circumstances her position ahead was the correct one. And where Simpson criticized the escorts for not firing Hedgehog in incidents where its use was appropriate, and for sometimes using inaccurate depth settings on D/Cs—“the errors have been pointed out to the vessels concerned”—Horton countered generously: “The skill and determination of all escorts engaged in this operation leaves little to be desired.” In that compliment he specifically included the Third and First Support Groups commanded by Captain McCoy and Commander Brewer, respectively, who “loyally gave complete cooperation with the Junior Officer in command of the close escort.” And to all involved he had earlier, on 6 May, sent a W/T message: “My heartiest congratulations on your magnificent achievements.”

Even by-the-book Simpson acknowledged the final showing as “a major victory,” and the fact that there were only two failures among the 340-odd D/Cs fired or dropped by B7 and its support elements he attributed to “a very high standard of depth charge efficiency in these groups, and [that] is definitely the result of stiff training.” In Horton’s comments on Simpson’s appreciation of the ONS.5 screen operations, the CinCWA judged that not only were those operations “a classic embodying nearly every method and form of tactics current at the time,” they probably marked the end of large U-boat pack attacks: “It may well be,” he wrote to the Lords Commissioners of the Admiralty, “that the heavy casualties inflicted on the enemy have gravely affected his morale and will prove to have been a turning point in the Battle of the Atlantic.” Like Winn, Horton may have been more optimistic than correct about the battle’s effect on German morale. But he was proved right on the second point: In the remaining twenty-four months of war no other U-boat group would attack with the same apparent pluck and confidence. The wolfpack mystique lay at ruinous discount.

How much Horton was now beginning to edge from a defensive to an offensive posture, as a result of this battle and subsequent events in May and early June, is exemplified by his relatively open response to a recommendation put forward on 9 May by Captain McCoy, SO, EG3, in Offa, who thought that evasive tactics, such as those employed in the long routing of ONS.5 to the north, were wasteful and unnecessary. Echoing Gretton’s confidence in the close screen, McCoy argued that, “Escorts that are fitted with radar and which are handled with determination, will always defeat the U-boat at night or in fog.” Therefore, he recommended directly to the CinCWA, “Our policy should be to invite the enemy to attack so that he can be destroyed.” This was to use merchant ships as bait, which Horton had rejected as “undesirable” in his Tactical Policy signal of 27 April. On 14 June, Horton responded (present writer’s emphases): “It is not agreed that it was desirable at the time this convoy was run to route convoys—particularly slow ones—so as to invite attack. If the changed situation which now prevails in the Atlantic were to be maintained, the routing of fast convoys when covered by support groups across the end of a patrol line so as to invite attack by a small number of U/Boats deserves consideration.… “ Even at that date, in mid-June, Horton was guarded and hesitant in his expressions, but in retrospect it is clear that his long-established policy of Defender was tentatively yielding primacy to one of Hunter.

On 13 May, the Newfoundland Daily News published a front-page article under the headline: 10 nazi subs destroyed in convoy attack. The account, datelined London the day before and transmitted by Reuters, was based on an Admiralty communiqué that did not identify the convoy but did give a summary of anti-submarine attacks by escort ships, which were named, and by RCAF aircraft, though the number of U-boats definitely destroyed in the story did not match up to the number in the headline. The Times of London ran basically the same story on the same day, but was more discriminating in citing the U-boat casualties as four destroyed, four very probably destroyed, and two probably destroyed. Following these two accounts, however, there was little public attention and even less scholarly notice given to the Battle for ONS.5. Prime Minister Winston Churchill, who was in Washington, D.C., at the time of the communiqué, sent a congratulatory message to the escorts via the Admiralty on 9 May—my compliments to you on your fight against the u-boats—but eight years later, in 1951, when writing the fifth volume of his history, The Second World War, the volume that treated of the Atlantic war in this particular period, he did not think the battle noteworthy enough to mention.57 Similarly, the official historian of Royal Navy operations during the war, Captain Stephen W. Roskill, D.S.C., R.N., devoted a mere page and a half to the battle in his three-volume history, The War at Sea, 1939–1945, published in 1956. To be fair, he allotted only twenty-one lines to the big battle of SC.122/HX.229 in the foregoing March.

Horton seems to have been the first to have grasped the decisive character of the ONS.5 triumph, suggesting that it would prove to be a “turning point” in the Atlantic struggle. Rodger Winn, in the OIC Tracking Room, wrote sometime within two and a half years of the battle: “This was probably the most decisive of all convoy engagements. It represented the extreme and, as it happens, the last example of coordinated pack attacks.” The Most Secret documents containing Winn’s appreciation were not released to the Public Record Office until 1975. In the meantime, Captain Roskill’s assessment of the place that this individual battle occupied in the war against Germany underwent a striking transformation. Where the most that he was willing to say in 1956 was that ONS.5’s “adventurous passage” had led to “grave losses” for the U-boats, three years later, in a review of Karl Dönitz’s Memoirs in The Sunday Times, he was emboldened to state: “[Dönitz] considers that the passage of convoy ONS.5 in April-May 1943 marked the turning point in the long struggle, and I fully agree with him.” Comparing Gretton and Sherwood to the likes of Hawke and Nelson, Roskill added this flourish: “The seven-day battle fought against thirty U-boats is marked only by latitude and longitude and has no name by which it will be remembered; but it was, in its own way, as decisive as Quiberon Bay or the Nile.” Perhaps, when viewed on the larger stage of World War II, it would not be unreasonable to say that the set-piece Battle for ONS.5 was the Midway of the Atlantic.

The pendulum of war, which had swung so dangerously to the German side in March and had reverted to center in April, now swung sharply to the Allies’ side. In reflecting on the long, bitter combat experienced by both belligerents during the passage of ONS.5, one’s attention is particularly drawn to the B7 flotilla that was the convoy’s original escort. In late April that force of seven warships, of which the majority were corvettes, set out to protect an argosy of forty-three light-ballasted ships whose best speed was seven and a half knots. Their passage would take them through bow-stopping gales and iceinfested seas. Their base course would be anticipated by German intelligence, resulting in their being attacked and chased at their northernmost position. They would have to pass through what remained of the Air Gap, with scanty overhead protection. And then they would fall into the fatal embrace of the largest U-boat attack force ever assembled against a single convoy—a force comprising as many U-boats as, at the time, the convoy and escorts had ships, and five times the number of RN defenders. By any objective standard their condition was desperate. Little wonder that Captain McCoy, whose EG3 had joined in support, said on 5 May that “the convoy was threatened with annihilation.” And merchantmen did suffer grievous losses. But B7 close escort ships alone exacted a heavy toll from their assailants, and supporting escorts, both surface and air, made additional U-boat kills. Every man who had been on board the B7 vessels, starting with Gretton, who drew up the game plan, and Sherwood, who executed it, down to the lowest ratings in the boiler and engine rooms, deserved the highest credit. Against all odds, the B7 ships and crews survived and prevailed. In the long Atlantic struggle against the U-boats, theirs truly was a sword-from-the-stone triumph. In looking through British naval/military annals for comparisons, one is tempted to recall Rorke’s Drift in 1879, where eighty men of the 24th Regiment of Foot defended the mission station against similarly overwhelming numbers. But Captain McCoy of EG3 will have the last word: “The skill, determination, and good drill displayed by all ships of B.7 Group during the time the Third Escort Group was supporting O.N.S.5 was beyond all praise."

Men of HMS Sunflower and HMS Snowflake

Crews of HMS Sunflower and HMS Snowflake together after passage of ONS.5

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  1. TO HUNT

The Bay in May

The effectiveness of the present sorties over the Bay can be raised from a low to a real killing effectiveness only when they become part of a larger organized and co-ordinated force, devoted to surprising, hanging on, and killing. STEPHEN RAUSHENBUSH

If we strike a decisive blow at the trunk in the Bay, the branches will wither. AIR MARSHAL SLESSOR

… take up arms against a sea of troubles, and by opposing end them. HAMLET, ACT III, SCENE 1

The U-boat has no more to fear from aircraft than a mole from a crow. ADMIRAL DöNITZ 4 AUGUST 1942

IT IS NOT KNOWN WHETHER forty-seven-year-old American economist Stephen Raushenbush had ever seen a submarine or a bomber before he was suddenly posted to London in December 1942 to help develop a new battle plan for the Bay of Biscay. Military tactics were not something in which he had had any great interest since 1917–1919, when he and most of his graduating class at Amherst College went to France with the American Expeditionary Force, he to serve as a volunteer ambulance driver. Though in that capacity he pursued his famous father’s compassionate ideals, he did not follow the Reverend Walter Raushenbush (1861–1918), a leading exponent of the Social Gospel, into the Baptist ministry. Instead, after the Armistice, he studied economics at the University of Rennes in France, worked in the oil industry in Mexico and Venezuela, researched coal and power issues in New York City, taught at Dartmouth College, and served for eight years as advisor on public utilities to the governor of Pennsylvania, while taking time out in 1934–1936 to be chief investigator for the Special U.S. Senate Committee that inquired into the munitions industry. In his spare time he wrote seven books, ranging in subject matter from The Anthracite Question (1923) to The March of Fascism (1939).

His last pre-World War II position, beginning in 1939, was with the U.S. Department of the Interior as chief of the Branch of Planning and Research in the Division of Power. He was described at that period of his life as a reserved but friendly person; he wore a mustache and smoked a pipe; though a registered Republican, he expressed political views that were liberal and progressive. Shortly after Pearl Harbor, he took a leave of absence from Interior to serve as a civilian economist and statistician in the office of the Chief of Naval Operations (CNO) in the Navy Department. From there, in late 1942, he was plucked by Captain Thorvald A. Solberg, U.S.N., Head of the Navy Technical Station, Office of the U.S. Naval Attaché (Alusna), London, to undertake air operations planning for the Bay of Biscay.

In the U.K., Raushenbush quickly familiarized himself with the attack opportunities in the Bay as well as with Coastal Command’s disappointing success rate there. Since June 1942 Coastal Command had flown about 7,000 hours and lost aircraft at a rate of about sixteen for every U-boat sunk in the Bay. Since October only twenty-two air attacks had been mounted on the estimated 290 boats that had passed through the Bay. The effort was out of all proportion to the meager results obtained. Raushenbush then set about studying the hardware. Near Glasgow on the Clyde he examined the Type VIIC U-570, captured in August 1941 and renamed HMS Graph, and learned her operating characteristics, paying special attention to the boat’s capacity for remaining submerged (36–41 hours) and the time required on the surface for fully charging her batteries (6.77–7.77 hours).

At various Coastal Command bases he studied the type of aircraft that were being flown on Bay patrols and took fascinated notice of new centimetric radar equipment that was just then becoming available for airborne use. At both Whitehall and Northwood he availed himself of the vast operations research data that had been accumulated by Professors Blackett and Williams and their scientific teams, whom Raushenbush found “tired and exhausted from too many seven day weeks.” From Williams in particular, who had continued Bay Offensive studies at Coastal during the year following Blackett’s departure for other ASW challenges at the Admiralty, and who was later quoted by Blackett as saying that while his scholarly specialty was quantum theory, he “found the subtle intricacies of the U-boat war of comparable intellectual interest,” the American economist drew generous guidance and support. In the end, not surprisingly, plans put forward to Churchill’s A.U. Committee by Raushenbush and Williams would bear a certain resemblance in conception, if not in details.

When he thought he understood the basic problems that the Bay presented, Raushenbush devoted himself to intense deskwork studies and statistical tables. His roommate at Alusna, Commander Oscar A. de Lima, U.S.N.R., remembered the economist’s “endless days and nights of complicated computations,” though the endless period was just over a month. Raushenbush’s interests were most closely focused on the new availability of “Most Secret” 10-centimeter airborne radar, for which the Germans had no search receiver (G.S.R.). According to a report submitted on 22 December by radar pioneer Watson Watt, the Kriegsmarine would probably not figure out the wavelength, develop an answering G.S.R., and install it in the majority of their boats before “two or three months at the most” after first use of the Allied equipment.

ASV Mark III Centimetric Radar

10 centimeter wavelenth Mark III air to surface radar , crucial to Battle of Atlantic

“There was great promise in this situation,” Raushenbush wrote privately in 1948. “The danger in it was that the new weapon might (like tanks in 1916) be used in too small numbers, with too small effect, and that the Germans would consequently be given ample notice of the new weapon before it could be used against them with telling effect, and would be ready for it.” He anguished, he wrote, over the possibility that a centimetric radar installation would first be used in an area such as the Mediterranean or the European mainland, where it might be captured and compromised. As it happened, a few Io-centimeter sets were flown by Coastal aircraft out of Gibraltar in February before their use in the Bay. And Raushenbush’s worst-case scenario—though it is not known that he was aware of it at the time—unfolded on 2 February when an RAF Bomber Command Stirling bomber equipped with centimetric radar went down at night near Rotterdam. The radar set was Type H2S, in which the radar pulses were used in a “look-down” mode for picking out coastlines, lakes, waterways, and (less successfully) cities.

Coastal had forcefully opposed that use of 10-centimeter radar prior to its use in the Bay precisely because capture of the equipment, which seemed likely, would ruin Coastal’s chances of obtaining surprise in the Biscay transit area. But Bomber Command spoke louder, claiming that for the success of the night-bombing campaign over Germany—always the overriding imperative in the Prime Minister’s mind—the bombers desperately needed H2S as a navigational aid. Churchill gave approval for the new radar’s use over enemy territory beginning in January 1943, with, as Coastal feared, predictable results. Though the Stirling’s radar equipment was badly damaged, German technicians were able to reassemble the Rotterdam Gerät, as they called it, at the Telefunken laboratories in Berlin. By chance, the device was badly damaged a second time in an RAF bombing raid. Again, it was reconstructed, this time in a bombproof bunker. After flight-testing the magnetron valve equipment, the technicians realized that the Allies had achieved a major technological breakthrough, and, where the maritime war was concerned, had leapfrogged the Fu.MB (Metox). News of the disclosure was passed at once to BdU, where on 5 May the Dönitz/Godt war diary reported a confirming incident at sea and ruminated on the “Rotterdam Gerät.”

“U-333 [Oblt.z.S. Werner Schwaff] was attacked by enemy aircraft at night without previous radar [detection by Fu.MB] in BF 5897. Slight damage, aircraft was shot down in flames.… [The aircraft was L/L Wellington “B” of No. 172 Squadron, which had just begun Bay patrols with ASV Mark III.] The enemy is working on carrier waves outside the frequency range of the present Fu.MB receivers. The shooting down over Holland of an enemy aircraft apparently carrying an apparatus with a frequency of 9.7 centimeters is the only indication at present of this possibility.”

The secret was out, and it appeared likely that the Germans would now neutralize the centimetric wavelength in the same way that Metox had neutralized the metric. But the Telefunken Company experienced problems in replicating parts of the Allied equipment, and administrative muddles further checked what was to have been a crash program to develop a new G.S.R., with the result, astonishingly, that an effective functional detector called Naxos-U prototype was not ready to the U-boats until December 1943, far later than the two or three months predicted by Watson Watt, and long after the issue in the Atlantic had been decided. (its trials and effective use by U-Boats would extend well into mid 1944)

Raushenbush began his calculations with a review of U-boat performance figures. The optimum (as against maximum) speed surfaced for charging batteries was 12 knots. The optimum speed for running submerged was 1.75 knots. The average battery capacity on entering the 200-mile-deep transit channel was 51 miles submerged, after which a U-boat had to surface for maximum recharge for a period of 6.77 to 7.77 hours, during which it would travel 81 to 93 miles. After another 51 miles submerged, it would have to surface for charging at least once again, briefly, until completing the 200 miles (assuming a direct course) in a total traverse time of 76.37 hours.

Thus, a U-boat in transit would be on the surface and vulnerable to air attack for at least one lengthy period. Any attempt to remain underwater beyond 41 hours would exhaust the air supply, although a boat could surface for 5 to 10 minutes to ventilate. A surfaced U-boat forced to dive by aircraft would later have to charge for approximately seven minutes to compensate for the 100 ampere hours used in one cycle of crash-diving and resurfacing. Since the average density of boats in the transit area at any given time was 15.8 boats, that number together would be exposed from 1,280 to 1,470 miles during their passage. Raushenbush calculated that there would be a density of one surfaced boat per 3,800 square miles.

On the air side, Raushenbush called for an additional 160 long-range aircraft, all equipped with ASV Mark III and many with Leigh Lights, to make up a total force of 260 aircraft. Such a large, coordinated force, trained to capitalize on the Allied advantage of centimetric radar, could be expected to make 7.5 sorties per aircraft per month, to make 1.8 attacks on each of 150 U-boats entering the transit channel each month, to make a minimum of twenty-five kills per month, and to cause damage to a further thirty-four boats. Over the projected 120 operational days of this effort, 100 boats would be destroyed and 136 damaged, thus “paralyzing” the U-boat fleet and throwing it on the defensive. The damaged boats would play their role in the paralysis effect by jamming and overloading the Biscay repair bases.

There were two critical factors in the Raushenbush Plan: (1) the attack program must be put into effect promptly, before the enemy devised a centimetric search receiver; and (2) the attacking force must be sufficiently large from the outset; “no small driblets” of additional aircraft would make the plan work. On the second point he elaborated that a law of increasing returns could be developed to show that up to a certain point, a large but still less than adequate force would produce only minor results; but that once enlarged to and beyond a certain critical mass, the effectiveness of that force was in high progression. He concluded:

“The morale of the remaining U-boat fleet may be broken by such an effort. If in four months (May-August 1943 inclusive) 100 U-boats are killed, and 136 damaged, and every one is attacked 1.8 times in transit, the U-boat fleet based on Biscay would have lost about 36 per cent of its numbers and the crews of an additional 136 would have been shaken up. The unkilled 175 U-boats may thereby be so broken in morale as to impair their effectiveness greatly.”

Raushenbush went on to suggest crew “mutiny” as a possibility, which was going somewhat over the top; the suggestion probably showed the degree to which his views were shaped by British associates, among whom the morale war seems to have been a preoccupation. One suspects, knowing how U-boat crews put out to sea unflinchingly in 1945, when certain to near-certain destruction faced every boat, that infidelity to duty in the U-Bootwaffe was never a consideration.

The Raushenbush Plan was endorsed by Captain Solberg, and, upon his recommendation, by Admiral Harold R. Stark, U.S.N., Commander, United States Naval Forces in Europe, who had it printed up for presentation to the Prime Minister’s A.U. Committee on 24 March. In the meantime, it received strong support from the operations research team at the Admiralty, though those politically savvy people knew that the Plan would not fly unless it passed the inspection of Churchill’s personal science advisor, Professor Lindemann, now Lord Cherwell. Accordingly, Professors Blackett and Williams (the latter now also with the Admiralty) joined Raushenbush to form a special committee under the chairmanship of Sir Stafford Cripps, Minister of Aircraft Production and vice-chair of the A.U. Committee, for the purpose of bringing Cherwell into camp. In that endeavor they were not entirely unsuccessful.

Cherwell was at first dismissive of the Raushenbush Plan as “based upon somewhat speculative foundations,” calling it “unduly optimistic.” Without directly challenging any of the American’s numbers or calculations, he rejected the “largely theoretical” proposals in the Plan as diverging from prior practical experience in the Bay, where the dividends had been very few. Furthermore, he argued, the presumed advantage of 10-centimeter radar would be overcome “very easily” by a new German search receiver; and the probability that the enemy would sprinkle the Bay with radio decoys seemed to have been treated “rather lightly” by Raushenbush. It would be better, Cherwell said, to devote aircraft resources to the more fruitful duty of protecting menaced convoys. In fact, better still would be the allocation of Coastal Command aircraft to the bombing of German cities, which “must have more immediate effect on the course of the war in 1943.” All that said, however, Cherwell did allow that it could be an “interesting experiment” to give the Raushenbush advocates a free run to see how they fared.

Two other events transpired before the plan devised by the U.S. Naval Attache’s one-man Bay research branch was formally presented. First, the Admiralty produced its own similar plan for the Bay. Second, a trial of the two plans was flown by Coastal Command from 6 to 15 February under the code name Operation Gondola. Although authorship of the Admiralty’s plan was credited to Blackett, he suggested in a eulogy of Williams (who died in 1945) that the calculations had been done by Williams during the winter of 1942–1943, when “he worked out in great detail the best methods of conducting such an offensive by a balanced force of day and night aircraft equipped with the latest forms of 10 cm. radar.”

Williams (or Blackett) shared the plan with Raushenbush, who drew up a one-page summary of comparisons and differences between the two sets of numbers. Both plans called for a total force of 260 heavy aircraft. Where Raushenbush estimated that the force required 160 additional aircraft, Williams estimated 190. Where Raushenbush envisioned a four-month offensive, Williams called for a full year’s endurance of effort. Both plans anticipated 150 U-boat transits a month in the Bay during spring 1943 (which proved to be too high). The average number of sorties per aircraft per month were approximately the same, as were the ratios of sightings to attacks, attacks to kills, and attacks to damaged U-boats. Where Raushenbush predicted twenty-five kills per month and thirty-four boats damaged, Williams anticipated twenty-two kills and twenty-two damaged.’

The nine-day Gondola trial did not exactly replicate either plan, since the aircraft of only three of the sixteen squadrons participating in whole or in part were equipped with 10-centimeter radar: these were United States Army Air Forces (USAAF) Liberator Squadrons Nos. 1, 2, and 224. Altogether, 136 individual aircraft, including L/L Wellingtons and L/L Catalinas, took part in standard patrols that “fanned” southward over the Inner Bay (East), where during the operational period forty U-boats traversed the area, and the Outer Bay (West), where thirty-eight boats transited. Eighteen sightings resulted (only two initiated by centimetric radar), leading to seven attacks. One U-boat was believed sunk by Liberator bomber “T” of No. 2 Squadron, but a recent NHB/MOD reassessment finds that the U-boat attacked, U-752 (Kptlt. Karl-Ernst Schröter), escaped serious injury. Still, the numbers, particularly those of sightings, and of the reduced flying hours required to make them, seemed provisionally to validate the Raushenbush/Admiralty Plans, taking into account the fact that most aircraft, as noted, were not equipped with centimetric radar. After the end of the operation there was a marked drop in the ratio of sightings to flying hours, back to the former low level.

In early March, to RAF Coastal Command’s great regret, U.S. Admiral King requested the transfer of two USAAF Liberator squadrons from St Eval in Cornwall to Morocco. Air Marshal Slessor stated that their crews had shown “intense energy and enthusiasm” in the anti-U-boat war, and “were just getting into their stride.” The loss of these centimetric-equipped aircraft as well as No. 405 Halifax Squadron, which had to be returned to Bomber Command, was a blow to both the Raushenbush and Admiralty Plans. Nonetheless, with the aircraft remaining, including this time the newly operational No. 172 Squadron of centimetric-equipped L/L Wellingtons, another combat trial in the Bay called Operation Enclose was laid on by Coastal for dusk 20 to dawn 28 March.

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