Battle of Atlantic - May-June 1941 , Codebreaking , US Intervention in Atlantic , Allied Shipbuilding and German Surface Raiders and Capture of Enigma Machine from a U-Boat (part 1)

from “Hitler’s U-Boat War” , Clay Blair Jr
“The War for the Seas” - Ewan Madsley
“Hitler’s U-Boat War” David Mason
“Atlantic Campaign” Van der Vat
“Donitz , The Last Fuhrer” - Peter Padfield
“Donitz andthe Wolfpacks” - Bernard Ireland

The U-boat campaign in the decisive North Atlantic area in the winter of 1940–1941 fell well short of what the Germans had expected. The U-boats sailing to that area in the five months from December 1 to May 1 sank only about 125 merchant ships for about 752,658 tons. This was an average of about 150,500 tons a month, sharply less than the monthly average attained in the “Happy Time,” May through November, 1940. Patrols to the South Atlantic area raised the total sinkings substantially, disguising the declining results in the north. The patrols to the south added about sixty-five ships for about 364,215 tons, raising the total of sinkings by all U-boats sailing in that five-month period to 194 ships for about 1.1 million tons. British shipyards in that same period produced less than half that tonnage, but the total loss was more than made up by the return to service of nearly 1 million gross tons of damaged shipping that had been idled in British shipyards.

Still , Whitehall , War Office in London continued to bemoan loudly the loss of tankers but in fact, the tanker losses in that five months were not overwhelming: twenty-seven ships for about 231,500 tons. Twenty-three of these tankers were lost in the North Atlantic; four in the South Atlantic. Of the total, twenty were British-owned; six were foreign ships on charter, and one was the Vichy French Rhone, sunk in error. Owing to the construction of new tankers in British yards,(British and Canadians built 77.000 ton of shipyards between last quarter of 1940 and first quarter of 1941) and to various Lend-Lease measures to supply American and other foreign tankers to the British (Norwegian mechant marine in exile had the largest tanker fleet of the world and on the whole passed to Allied service after invasion of Norway , which was a big blow to tonmnage war goals of German Navy) , and to the participation of American ships in the Caribbean–East Coast “shuttle,” the oft-predicted oil crisis in the British Isles did not yet occur, according to the official British oil historian, D. J. Payton-Smith.

It was not yet apparent, but by the end of April 1941, the Battle of the Atlantic in northern waters had turned slightly in favor of the British, at least for the nonce. Under operational control of the British dmiralty, RAF Coastal Command had built air bases in Iceland and the Faroes, extending daytime air escort of inbound and outbound convoys ever westward. No Coastal Command aircraft had yet sunk a U-boat unassisted, but the increased air coverage gave warning of U-boats to the convoy surface escorts, drove the U-boats off, and held them down, frustrating shadowers and the assembly of packs. The Escort Groups shuttling between the British Isles and Iceland, and those based at Iceland, likewise presented a menacing obstacle. With increasing numbers of escorts available, it was now possible to detach one or more warships to hunt and drive off the convoy shadower and to counterattack and hold down the attacking U-boats, preventing a second attack while the convoy evasively altered course. Inasmuch as U-boats avoided rather than attacked enemy air and surface escorts, with each passing month the escort crews gained more experience and skill in U-boat hunting, while the experience and skill of the U-boat crews declined, a trend that was certain to continue unless the Germans found some means of attacking the escorts.

More difficulties lay ahead for the U-boats. The British intelligence had penetrated German Naval Enigma wireless coding. Should the British Admiralty’s other planned captures succeed (as we shall see most did) , Bletchley Park, employing increased numbers of Turing-Welchman bombes, stood a good chance of a really decisive break into naval Enigma. The number of primitive (but useful) 1.5-meter-wavelength radar sets in Coastal Command aircraft and surface escorts was steadily increasing. New electronic devices were nearly ready for mass production: the greatly improved centimetric-wavelength radar for aircraft and surface vessels, employing the Randall and Boot cavity magnetron; miniaturized High Frequency Direction Finding (HF/DF, or Huff Duff) sets, suitable for installation on convoy vessels, enabling them to home on high-frequency radio transmissions from nearby U-boats ; and greatly improved radio gear for communications between the surface escorts (Talk Between Ships, or TBS) and between the surface escorts and air escorts, the latter an important advance usually overlooked in accounts of the U-boat war.

On top of that week by week the United States had become more deeply involved in the Battle of the Atlantic. After passing Lend Lease Bill and signing it , President Rosevelt was trying to find new ways to aid Britain and its war effort. In addition to the measures already described, in response of Hitler’s decleration of Atlantic waters west of 36 parallel would be operational zone for German Navy , on April 18 US Atlantic Fleet commander Admiral Ernest King grandly declared that the waters of the “Western Hemisphere,” for which he was responsible, now extended eastward to approximately 26 degrees west longitude (a line just west of Iceland and south to the Azores) and stated in effect that any transgression of that line by the Axis powers would be viewed as “unfriendly.” In response to requests (read directives) from London, the Canadians, too, were poised to enter the Battle of the Atlantic for the first time in an important way. Pending the arrival of the destroyers of the American Support Force, the Canadians were to assume responsibility for convoy escort in Atlantic home waters and out to 35 degrees west, where the spliced-in Iceland-based British escort groups took over the convoys. For this purpose, the Canadians established the Newfoundland Escort Force, some thirty-eight warships,(thirtheen destroyers , four sloops and tenty one corvettes) commanded by a Canadian, L. W. Murray, based at St. John’s. It was supported by twenty-four American-built aircraft in two squadrons of the Canadian Eastern Air Command.

Since improved British ASW measures in the Northwest Approaches made it necessary to again operate the Type VIIs ever farther westward, incurring the penalties imposed by fuel limitations, Dönitz needed far more U-boats to regain the upper hand than he or anyone had ever envisioned. Not just 300, but perhaps twice that number. U-boat production was increasing dramatically: Forty-three new boats were commissioned in the four-month period January–April 1941, but owing to the usual four months required for workup, these were not to reach the Atlantic in substantial numbers until June and beyond. Even assuming modest combat losses and a maximum production rate, rising to twenty or more boats per month in the second half of 1941, by the beginning of 1942 Dönitz could expect to have no more than about 100 oceangoing boats of all types for Atlantic operations. Given the accelerating rate of aircraft, escort, and ship production in Great Britain, Canada, and the United States, the late-starting and lagging U-boat production, and ever-declining experience levels of U-boat crews, Dönitz was to be hard-pressed to regain the upper hand in the Battle of the Atlantic by 1943 or ever. And yet there was not the slightest sense of defeat among the staff at Kerneval. Even discounting the skipper overclaims, it was clear that the small U-boat arm was causing terror and significant harm to British maritime assets and forcing a great expenditure of Allied resources to counter the threat. Convoying alone—as Churchill repeatedly lamented—had reduced Great Britain’s imports by “one-third.” It was not actually that bad (wartime raw material transport for war production , oil and food import actually slightly increased ), but bad enough because necessary sea transport tonnage for these imports was not decreasing significantly as Donitz hoped to starve British war effort but not increasing fast enough either for Britain and her Allies to expand its war capabilities faster…

While Operation Barbarossa (invasion of Soviet Union ) was being prepared in first half of 1941 and Germans entered Balkan/Mediterranean Theaters , the Kriegsmarine was to continue pressure on the British, tying down naval and air forces and blocking any and all British attempts to assist the Soviets, such as another invasion of Norway. But on per to Hitler’s orders , all U-boats and merchant-ship raiders were to take special pains to avoid any “incident” with the United States that might provoke Washington to open intervention during Barbarossa. Commencing in late May 1941, newly commissioned Type VII U-boats departed the Baltic for battlefronts in ever increasing numbers: twelve in June, nine in July, twelve in August. This was a far cry from the “twenty-five to thirty” new U-boats per month envisioned in the construction programs of 1939 but double or triple the usual monthly rate of new arrivals in the Atlantic, and therefore the first significant increase in force levels since the onset of war. Owing to the slight battle losses incurred from December 1940 to May 1, 1941 (seven), and to a continuation of that modest trend through the summer months, Dönitz had the means not only to intensify the U-boat war in the “decisive” North Atlantic arena, but also to send another wave of Type IXs to the promising waters of West Africa (during March a four U-Boat group pack created havoc on West African shores across Sierra Leone and Freetown , sinking 34 mostly single sailing merchant ships totalling appox 129.000 tons of shipping in five weeks and on top of that torpedoing a damaging Queen Elisabeth Class battleship HMS Malaya which had to be sent to US East Coat for damage repair. There were weak spots like that in British shipping lanes across the globe) .

However , the first important event of the Battle of Atlantic during 1941 , occured in 3 May 1941 , Tribal class Royal Navy destroyer HMS Somali intercepted and captured German weather ship Munchen in North Sea. German crew had thrown their Enigma machine overboard before boarded by British boarding party but after overtaking the Germans , British naval personnel discovered most of the Enigma keypads , cribs and short signal documents were intact. These were all gathered up along with intanct Munchen and brought to Scapa Flow , from there Enigma materiel captured was sent to Goverment Cypher School in Bletchley Park where along wqith all material and Enigma machine captured from U-110 (as mentioned below) together , they would prove an immense treasure hove for British crypto analysers.

Nineteen U-boats sailed to the North Atlantic in May. The first, U-94, a VIIC commanded by Herbert Kuppisch, reported a convoy south of Iceland on May 7. This was Outbound OB 318, which had sailed from the British Isles with thirty-eight ships. It was heavily guarded by Escort Group 7, commanded by I. H. Bockett-Pugh, composed of ten warships: three destroyers (including the ex-American four-stacks Campbeltown and Newmarket), five corvettes, a sloop, and an ASW trawler. Coastal Command aircraft from Iceland and Scotland provided air cover. Per plan, three ships had left the convoy earlier that day to put into Iceland. Five other ships, including the 10,000-ton liner Ranpura, an armed merchant cruiser, had joined, making a total of forty ships. At the time Kuppisch detected the convoy, a complicated change-up in the escort for Outbound OB 318 was in progress. Escort Group 3, commanded by Addison Joe Baker-Cresswell, had sailed from Iceland to relieve Bockett-Pugh’s Escort Group 7 for the middle leg of the trip. Composed of nine warships (three destroyers, three corvettes, three ASW trawlers), Escort Group 3 had in company the auxiliary cruiser Ranpura and four freighters that were also en route from Iceland to join OB 318. To assure a safe changeover of the escort groups, the sloop Rochester and five corvettes of Bockett-Pugh’s Escort Group 7 were to remain with the convoy for an extra twenty-four hours before going to other duties. Hence there were fifteen warships in the vicinity of OB 318. It was a bright moonlit night and, after broadcasting the convoy contact, Kuppisch elected to attack submerged. He let the lead escorts pass and gained a position in the middle of the convoy, “between two 10,000-ton liners,” probably the British ships Ranpura and Ixion. He then fired four torpedoes into the columns of ships. He claimed sinking four vessels for 20,000 tons, but actually only two sank: the 10,300-ton Ixion and a 5,700-ton Norwegian freighter. The flagship of Escort Group 3, the destroyer HMS Bulldog, joined by the destroyer HMS Amazon and the Escort Group 7 sloop HMS Rochester, pounced on U-94 and, during four hours, dropped eighty-nine depth charges, “a severe and accurate counterattack,” Kuppisch logged, “which caused considerable damage.” The counterattack prevented a second attack by U-94, but Kuppisch repaired the damage and continued his patrol.

Acting on Kuppisch’s contact report, Dönitz alerted six other boats that were patrolling west of Iceland. Two boats found the convoy in bright moonlight during the night of May 8: Fritz-Julius Lemp in U-110, from Lorient on its second patrol, and the new VIIC U-201, commanded by Adalbert Adalbert (“Adi”) Schnee, who began the war as first watch officer of Kretschmer’s U-23 and later commanded the ducks U-6 and U-60. Lemp had been on patrol three weeks and had sunk one 2,500-ton freighter. Sailing from Bergen, Schnee had been on patrol one week. He had polished off the abandoned hulk of the tanker Capulet (wrecked by Topp in U-552) and possibly a 2,000-ton steamer. Lemp and Schnee met on the morning of May 9, ahead of the convoy, which at that time had no air cover. Since a bright moon was expected again that night, they agreed that a surface attack would be dangerous. And since they assumed that by then the escorts had left the convoy, the two skippers (communicating by signal flags) elected to attack submerged in daylight as soon as possible, possible, to avoid the possibility of losing the convoy. The senior man (and Ritterkreuz holder) Lemp was to go first; Schnee was to attack half an hour later, after the convoy had been thrown into confusion by Lemp’s attack.

Lemp submerged and let the convoy come on. Surprised to see the escorts, he nonetheless decided to continue with the attack. At about noon, he hit the convoy’s right flank, setting up on four different ships, three of which he believed he sank. In actuality, two British freighters, the 5,000-ton Esmond and the 2,600-ton Bengore Head, went down. The fourth torpedo misfired, but after it had been readjusted, Lemp prepared to shoot at a tanker. The convoy executed an emergency turn to port and when Schnee attacked about thirty minutes later, he shot into what was then the rear , of the formation. He hit two 5,900-ton freighters, the Gregalia, which sank, and the Empire Cloud, which was severely damaged and abandoned, but later salvaged and towed to Scotland.

At the time of these attacks, the convoy was guarded by the nine warships of Baker-Cresswell’s Iceland-based Escort Group 3. The flagship, the destroyer HMS Bulldog, along with the ex-American four-stack destroyer HMS Broadway and one of the three corvettes, HMS Aubrietia, hunted U-110, which was still at periscope depth, preparing to shoot at the tanker. All three escorts obtained firm sonar contacts. HMS Broadway attacked, dropping a single depth charge. Seeing Lemp’s periscope, HMS Aubrietia, commanded by V. F. Smith, attacked it twice, dropping sixteen well-placed depth charges set for 100 and 200 feet.

The depth charges from Aubrietia fell very close to U-110. The blasts smashed the diving gauges and other instruments, knocked out the electric motors, diving planes, rudder, and compass, ruptured an aft fuel or ballast tank, sheared off the high-pressure air valves in the control room, and generated chlorine gas in the forward battery. Flooding aft, the boat went out of control and slid stern first to 300 feet. Seeing that U-110 was beyond all hope, Lemp ordered the engineer to “prepare for emergency blow,” which would bring them up. But before he could give the order, Lemp and the crew felt an “unexpected rocking motion,” indicating that the boat had surfaced of its own accord, perhaps owing to a rupture in a high-pressure air line, which blew the ballast tanks.


CAPTURE OF U-110 AND ALL OF ITS ENIGMA MATERIEL BY ROYAL NAVY (One of the main turning points of Battle of Atlantic)

Lemp (same Captain Julius Lemp who sunk passanger ship Athenia in September 1939 ) rushed to the bridge to find a terrifying sight: HMS Bulldog, HMS Broadway, and HMS Aubrietia close at hand, all firing at U-110 with every available weapon. Bulldog and Broadway were coming in at full speed to ram. Lemp shouted: “All hands abandon ship as fast as possible!” There was no time to connect the detonation charges for scuttling. The fastest way to scuttle was to open the ballast-tank vents. The first watch officer, Dietrich Loewe, who was in the control room with the engineer, Hans-Joachim Eichelborn, remembered that Lemp next shouted: “Open the vents” and that Eichelborn did so. But something went wrong. Either Eichelborn failed to carry out the order or the controls malfunctioned. The vents remained closed.

There were forty-seven men on board U-110. In response to the cry “abandon ship,” all hands rushed pell-mell to the bridge in such haste that the radio operator did not take time to destroy or bring the Enigma and code materials with him, and a war correspondent, Helmut Ecke, left behind his still and movie cameras and film. Climbing down on deck through murderous British gunfire, the men dived over the side into the icy water. Loewe remembered that although two men had been wounded, all hands got away from the boat “alive” and that he and Lemp and Eichelborn were the last to leave the bridge. They did not do so, he said, until the water was “one meter above the base of the conning tower” and they were certain that U-110 was going down.

Coming in to ram with all weapons blazing, the Escort Group commander, Baker-Cresswell in HMS Bulldog, noted that U-110 was down by the stern but did not appear to be sinking. Believing he might get a boarding party on her or even capture the boat, he ordered full-speed astern to cancel the ramming and in the same breath summoned the boarding party. At about the same time T. Taylor, skipper of Broadway, got the same idea and also canceled his ramming. To panic the German crew, hasten the evacuation of the boat, and thereby possibly prevent scuttling, Taylor came right up to U-110’s bow and dropped two shallow-set depth charges. In the process, however, HMS Broadway fouled U-110’s bow plane, which cut a deep gash in the destroyer’s thin side plating (flooding ten oil tanks and the forward magazine) and damaged the port propeller. The terrific blast of HMS Broadway’s two depth charges may well have caused panic inside U-110 and added momentum to an already frenzied evacuation.

Exactly what transpired in the next few minutes is a matter of lasting controversy. Loewe stated that after he and Lemp were in the water, they saw the bow and conning tower of U-110 lift “high out of the water,” indicating that she had not sunk! “Let’s swim back on board ship,” Lemp yelled, according to Loewe. Lemp’s apparent aim was to open the vents or set off the demolition charges to assure scuttling or, perhaps, at least to throw the Enigma and coding materials over the side. But U-110 had drifted off too far; they could not return to the boat. They turned around, Loewe said, and swam toward HMS Bulldog, which was lowering a whaler manned by a heavily armed boarding party.

At this point, Lemp disappeared from the scene. Some German submarine veterans, most recently Peter Hansen, insist that the boarding party, en route to U-110 in the whaler, spotted Lemp in the water and that one of the members of the party “promptly shot” him to prevent any interference with the mission and to conceal the fact that the British boarded U-110. (The correspondent, Helmut Ecke, claimed that the British shot at him while he was in the water.) Others say that Lemp threw up his arms in despair and disappeared beneath the waves, an apparent suicide. The Admiralty has said only that Lemp and fourteen enlisted men died in the sinking.(Lemp was a Ritterkreuz winner ace after Prien , Kretschmer and Schepke and a highly sucessful submarine skipper so it is not very convincing British boarding party shot him when they could easily capture him instead and under interrogation in UK , he could provide valuable intelligence)

Intent on raiding or capturing U-110, Baker-Cresswell in Bulldog and Taylor in HMS Broadway made no effort to fish the Germans from the icy waters. Smith in HMS Aubrietia, who had temporarily lost his sonar, hauled out of the area to make repairs. While doing so, he rescued forty-nine survivors from the lifeboats of the freighter Esmond, sunk by Lemp. The Germans were left to fend for themselves for about two hours. Many died of wounds, hypothermia, and shock, or drifted out of sight. The boarding party from Bulldog, commanded by twenty-year-old Royal Navy Sub-Lieutenant David E. Balme, rowed the whaler right up on the forward deck of U-110. Carrying Lee Enfield rifles and pistols, the nine men jumped out and spread around the deck and bridge to shoot any Germans who might attempt to interfere with the mission. To Balme’s astonishment, both the conning-tower and control-room hatches were dogged shut, not what one would expect of a scuttling U-boat. Pistol drawn, he opened the hatches, expecting to confront crewmen below. But the boat was deserted. Increadibly Royal Navy had her first enemy submarine captured almost intact due to her captains panic and misjudgement.

All hands had abandoned ship. All the lights were on, burning brightly; there was no sign of flooding or any indication of chlorine gas. After a hurried inspection, Balme signaled Baker-Cresswell on HMS Bulldog that the U-boat appeared to be “seaworthy and towable” and requested that he send an engineering party to operate U-110’s machinery. Baker-Cresswell directed Taylor on HMS Broadway to send an engineer to U-110 via whaler, then eased HMS Bulldog close to U-110 to receive an old, rusty 2″ steel cable that two of Balme’s men had found in a topside locker on the U-boat. Meanwhile, belowdecks, Balme and the other six members of his party were collecting intelligence items of incalculable value. Balme described that work in a secret report to the Admiralty. In part:

"The U-boat had obviously been abandoned in great haste as books and gear were strewn about the place. A chain of men was formed to pass up all books, charts, etc. As speed was essential owing to the possibility of the U-boat sinking (although dry throughout) I gave orders to send all books, except obviously reading books, so consequently a number of comparatively useless navigational books, etc., were recovered. All charts were in drawers under the chart table in the control room; there were also some signal books, log books, etc. here. … Meanwhile the telegraphist went to the W/T [radio] office just forward of the control room on the starboard side. This was in perfect condition, apparently no attempt having been made to destroy any books or apparatus. Here were found C.B.s [codebooks], Signal Logs, pay books, and general correspondence, looking as if this room had been used as a ship’s office. Also the coding machine [Enigma] was found here, plugged in as though in actual use when abandoned. The general appearance of this machine being that of a typewriter, the telegraphist pressed the keys and finding results peculiar, sent it up the hatch."*

The convoy, meanwhile, had pressed on, guarded by the destroyer HMS Amazon, two corvettes, and two ASW trawlers. HMS Amazon got a sonar contact on Schnee’s U-201 and called in the corvette HMS Nigella and the trawler HMS St. Apollo. The three vessels fixed U-201 on sonar and pounded her with depth charges for about four hours. Schnee and his men counted ninety-nine explosions. Some of these caused extensive damage to U-201, including a serious leak in an external fuel-oil tank, which helped the escorts track the boat. Finally, Schnee got away—without again having seen U-110. That night he reported his successes and battle damage to Kerneval, adding that since he had seven torpedoes left, he would make every effort to repair the leak and continue the patrol. And he did.

Left far behind with U-110, Baker-Cresswell in HMS Bulldog believed he had a good chance of towing the boat to Iceland. He finally got the 2″ steel cable from U-110 and attached it to his own ship. Upon boarding the boat, the engineering party from HMS Broadway, led by G.E. Dodds, found her to be fully
“intact,” with a “negligible quantity of water in the bilges.” However, there were two problems: the port shaft of U-110 was turning over slowly, and there was a “slight bubbling noise” aft. Unable to read German, Dodds could not stop the port electric motor or start the starboard motor to equalize the forward motion. He attributed the “bubbling noise” to a leaking ballast- or fuel-tank vent, perhaps damaged by the depth charges. Unfamiliar with submarines, he could not blow that tank. If the venting continued, the tank would flood completely, taking U-110 down by the stern.

Meanwhile, HMS Aubrietia returned to the scene and commenced fishing the Germans from the water. Altogether she rescued thirty-four men, including the first watch officer, Loewe, the engineer Eichelborn, the second watch officer Ulrich Wehrhrofer, and the war correspondent Ecke. All the Germans were hurried belowdecks to distance them from the angry survivors of sunk merchant vessel Esmond and to conceal from them the boarding of U-110. Two Germans died on board HMS Aubrietia due to their wounds , leaving a net bag of thirty-two prisoners.

As HMS Aubrietia was pulling the last German on board, HMS Bulldog reported a firm sonar contact. Baker-Cresswell cast loose the steel towing cable and called up the damaged HMS Broadway and HMS Aubrietia. The three vessels attacked the contact for an hour and a half, dropping thirty-two depth charges, and causing some anxious moments for the British boarding parties inside U-110. However, no evidence of a kill could be found and later this contact was classified as “doubtful.” The hunt was terminated and the salvaging of U-110 resumed. To conceal the capture of the U-boat from the survivors of Esmond and U-110, Baker-Cresswell ordered HMS Aubrietia to leave the area and find the destroyer Amazon, and transfer all survivors and prisoners to her. Baker-Cresswell in HMS Bulldog reattached the old, rusty steel cable to U-110, which by then was heavily down by the stern. Having been aboard U-110 for about five hours and having ransacked her of everything useful and interesting (including six sextants and ten pairs of Zeiss binoculars, Ecke’s cameras, and Lemp’s Ritterkreuz), Balme’s boarding party—and engineer Dodds’s party from Broadway—closed all watertight doors, dogged down all hatches, and returned to their ships. Escorted by the damaged HMS Broadway, HMS Bulldog headed for Iceland—400 miles distant—towing the yawing U-110 at a speed of 6 knots. All went well for about seventeen hours—about 100 miles—but at 11:00 the following morning, March 10, all abandoned U-110 suddenly upended and sank, “her bow standing vertically out of the water.” The loss, Baker-Cresswell wrote, was a “bitter blow.”

In the dark of that same morning, March 10, far to the west, a new VIIC, U-556, commanded by Herbert Wohlfarth, from the ducks U-14 and U-137, caught up with the convoy. Wohlfarth attacked on the surface, firing two torpedoes at two different ships. He claimed both ships sank, but in fact, he had hit only one, for damage. The convoy dispersed, but Wohlfarth hung on looking for strays, and later that day, attacking submerged, he torpedoed and sank a 4,900-ton British freighter. Still later he stopped a 5,100-ton Belgian freighter with one torpedo and finished her off with his deck gun. Based on flash reports from three of the boats and from distress calls picked up by B-dienst, Dönitz concluded that the four boats which had attacked convoy OB 318 had sunk thirteen ships for 76,248 tons. The confirmed result was about half the claim, seven ships sunk for 39,255 tons: two by Kuppisch in U-94; two by Lemp in U-110; two by Wohlfarth in U-556; and one by Schnee in U-201. As a result of these and past overclaims and credits, Kuppisch and Wohlfarth were awarded the Ritterkreuz.


Baker-Cresswell in HMS Bulldog reached Iceland late on March 10. He transferred the thirty-two German prisoners from HMS Amazon to HMS Bulldog and the next day set off for Scapa Flow, making 25 knots to avoid any possibility of a U-boat attack. En route he talked individually and cagily with the three German officers and the correspondent Ecke, to see if any of them had an inkling that U-110 had been boarded or taken in tow. Apparently none did. Nor did any of the enlisted men, who were canvassed in a similar manner by the crewmen of HMS Bulldog. Since some of the Germans had seen Bulldog launch the whaler with the boarding party, Baker-Cresswell and his crew put about a “cover story” that U-110 had “sunk” before it could be boarded. (crews of HMS Bulldog , HMS Broadway and HMS Aubrietia and rescued survivors of Esmond who witnessed or participated boarding of U-110 were all sworn secrecy. Remarkably no wording of boarding leaked till naval historian Stephen Roskill wrote a slim book about it “Secret Capture” in 1959.

The intelligence haul from U-110, which filled “two packing crates,” was eye-popping and historic and no doubt kind of intelligence material that would change course of war : a working naval Enigma machine, the keys for Heimisch (the Home Waters or Dolphin code) for April and June, the keys to the double-enciphered Offizierte (Officers-Only) code, a book containing the Kurzsignale (Short Signal) code, and Kriegsmarine grid charts, as well as special charts showing the safe routes through German minefields in the North Sea and along the French coast, decoded U-boat traffic (in Heimisch) for the period April 15–May 9, administrative correspondence, a complete set of technical manuals and diagrams of all the Type IXB fuel, air, hydraulic and other systems, and hundreds of mundane items, down to the citation for the award of the Iron Cross Second Class to the engineer, Eichelborn. After he had been briefed on the haul, First Sea Lord Dudley Pound telexed Baker-Cresswell, who had codenamed the boarding Operation Primrose: “Hearty congratulations. The petals of your flower are of rare beauty.”

The current Heimisch keys for May, printed on water-soluble paper, had apparently been destroyed by the Germans or possibly lost or ruined during the transfer to HMS Bulldog. Hence it was not possible for Bletchley Park to read Heimisch currently until June. Duplicate Heimisch keys for June were obtained when, in a well-planned action, a British naval task force captured the 300-ton German weather-reporting trawler München on May 7. The Admiralty showered praise and awards on all those concerned with the victory over U-110. Pound immediately promoted Baker-Cresswell from commander to captain. In a special ceremony at Buckingham Palace, King George VI appointed Baker-Cresswell and HMS Aubrietia captain, Smith, Companions of the Distinguished Service Order (DSO). He awarded Balme, Dodds, and the captain of HMS Broadway, Taylor, the Distinguished Service Cross (DSC). Three others received the Distinguished Service Medal (DSM) and fourteen officers and men were “Mentioned in Dispatches.” When the King gave Dodds his DSC, the official naval historian wrote, the King told Dodds the operation “was perhaps the most important single event in the whole war at sea.”

Although British intelligence officers stressed to the German prisoners the cover story that U-110 had sunk before it could be boarded, the first watch officer, Loewe, was not fully convinced. He remembered that he had talked to six of the U-110 crewmen on HMS Amazon or HMS Bulldog and that “none” had actually seen the boat sink. Loewe’s suspicions were fully aroused when the British gave the engineer, Eichelborn, the citation for his Iron Cross Second Class, which, Eichelborn believed, he had possibly left “in a folder in the control room.” If so, the British had certainly boarded U-110. Loewe remembered that he then discussed the matter with the senior German POWs, Otto Kretschmer and Hans Jenisch, and that it was decided that Loewe should inform Dönitz.

Before the war, Dönitz had adopted a coding system which officer POWs could incorporate in letters to their families via Red Cross. It was a duplication of a World War I submarine POW code, in which the arrangement of the first letters of certain words stood for the dots and dashes of Morse code. The families were under instructions to forward all POW mail to Dönitz, who would examine the letters for important encoded information, such as the cause of the loss of the boat, torpedo failures, and so on.

The British had broken this relatively simple code in World War I and were not surprised when it resurfaced in World War II. Hence they “read” all encoded information going back to Dönitz. From this flow of encoded mail, they gleaned inside information not otherwise revealed, some of it quite useful. They also used the mail code as a channel to funnel “disinformation” to Dönitz and for other purposes. Actually British counter intelligence MI5 , returned Eichelborn’s medal citation to him to test if the cover story on U-110 was working among the Germans. That is, to provoke a reaction of some kind that would indicate what the Germans really knew. Falling for this gambit, Loewe encoded a letter to his family for Dönitz, employing the prearranged designation for U-110, which was U-E-O. In his letter Loewe encoded the message: “Suspicion U-E-O in enemy hands.” The British, of course, confiscated this letter , changed its contents that “U-E-O is not in enemy hands” and intensified efforts to persuade the U-110 survivors that the boat had not been boarded. Unaware of what had transpired on U-110, Lemp died a hero in German eyes and, as was customary, Dönitz named a barracks in his honor in Lorient.


Altogether the U-boats sank seven empty freighters for about 40,000 tons from convoy OB 318 and damaged two other freighters, both of which made port. But after that battle, the boats in the North Atlantic were again hard-pressed to find targets. Between May 10 and May 20, they sank only four ships. The most notable of these was the 10,500-ton auxiliary cruiser Salopian, by Robert Gysae in U-98; the least notable was a 500-ton French sailing ship gunned under by Wolfgang Lüth in the old Type IX U-43, which had sunk at dockside in Lorient in early February and was finally back in action. Returning to Lorient after a thirty-two-day patrol, Ritterkreuz holder Karl-Heinz Moehle in U-123 reported sinking merely one ship (in April). Judging that Moehle had “health” problems, Dönitz relieved him of command and sent him to the Training Command.

In search of convoys beyond reach of Iceland-based air and surface escorts, Dönitz moved the bulk of the boats ever westward. By May 19, nine patrolled a line at 41 degrees west, directly south of Greenland. Late that afternoon, Herbert Kuppisch in U-94—who had earlier found convoy Outbound OB 318 and won a Ritterkreuz—intercepted convoy Halifax HX126, escorted by only one auxiliary cruiser. Upon receiving the report, Dönitz instructed Kuppisch to shadow and withhold attack until the other boats came up.

Commencing at 0400, May 20, the boats struck, Kuppisch first. He fired two torpedoes at one target but both missed. Speeding onward into the center of the convoy, the torpedoes hit two other ships, both of which sank. Later that afternoon Kuppisch sank a 6,100-ton Norwegian tanker, John P. Pedersen.

Five other boats had successes. Herbert Wohlfarth in U-556, still on his first patrol, sank the 8,500-ton tanker British Security and a 5,000-ton freighter, and damaged a 13,000-ton British tanker. Hans-Georg Fischer in a new IXB, U-109, sank a 7,400-ton freighter. Wilhelm Kleinschmidt in another new IXB, U-111, sank a 6,000-ton freighter. Robert Gysae in U-98 sank a 5,400-ton freighter and damaged another. Claus Korth in U-93 wrecked and set on fire the 6,200-ton tanker Elusa. Counting past overclaims, the sinking earned Korth a Ritterkreuz.

Upon receiving the first distress call from the convoy, the Iceland-based Escort Group 12, commanded by C. D. Howard-Johnston, raced west. Consisting of eleven warships (five destroyers, four corvettes, two ASW trawlers), it arrived to find the convoy dispersed and utterly disorganized. Howard-Johnston, in the destroyer HMS Malcolm, deployed the escort group to round up the scattered ships and reform them into a convoy. One of the corvettes, HMS Verbena, commanded by Captain Denys Arthur Raynor, was ordered to tow the smoldering hulk of the tanker Elusa to Iceland, if at all possible. Closing on the hulk, Raynor was astonished to see a U-boat on the surface also approaching Elusa. Giving the alarm, HMS Verbena opened fire, forcing the boat to dive. Upon reaching the site of the dive, Verbena dropped five depth charges, while the ex-American four-stack destroyer Churchill came up to assist. Both ships got a firm sonar contact and both conducted repeated depth-charge attacks. The records are not clear, but the U-boat was probably Eitel-Friedrich Kentrat’s U-74, fresh from France. At this time Kentrat reported such “heavy” depth-charge damage that he was forced to abort to Lorient.

When Dönitz learned from one of the U-boats that “five destroyers” had come up to escort the convoy, he ordered all boats to break off the attack and reform a patrol line farther south. He left one boat in northern waters, Kleinschmidt’s new U-111, to transmit a series of “dummy” radio messages, designed to make the British think the pack was still stalking convoy Halifax HX 126 eastward and trick them into routing the next convoy south, into the arms of the reformed patrol line. This was the first known instance in which Dönitz employed “radio deception.” While carrying out the deception on May 22, Kleinschmidt encountered and sank a 4,800-ton freighter sailing alone. Based on flash reports from the boats, Dönitz concluded that the pack had dealt convoy HX 126 a severe blow: nine ships sunk for 71,484 tons. He was correct. The six boats had sunk nine ships, but, as usual, the tonnage was inflated. The confirmed total was 54,451 tons sunk, including the tanker Elusa, which could not be salvaged, and the other two tankers, plus damage to another tanker.