from naval history net
JANUARY 1941
German Heavy Warships & Raiders - Pocket battleship “Admiral Scheer” was hunting in the South Atlantic, while battlecruisers “Scharnhorst” and “Gneisenau” in Germany and heavy cruiser “Hipper” in Brest, France prepared to sail. At the end of the month on 29th January the two battlecruisers headed out into the Atlantic for two months operations before returning to Brest. (Operation Berlin) Six of the original seven raiders were still at sea - “Orion” and “Komet” in the Pacific, “Atlantis” at the desolate island of Kerguelen in the southern Indian Ocean, “Kormoran” in the central and “Thor” in the South Atlantic. Finally “Pinguin” was in the Antarctic. All six moved to different areas over the next few months. Until June 1941, German warships sank 37 ships of 188,000 tons and raiders 38 ships of 191,000 tons. Thereafter neither type inflicted many losses as worldwide convoys were organised and the raiders’ supply ships sunk.
**7th January - Italian submarine “NANI” attacked a convoy west of North Channel and was sunk by corvette HMS Anemone. At the other hand German U-Boats could locate only one convoy slow moving SC-19 in North Atlantic and three U-Boats gathered could sink only six ships totalling 39.000 tons. Other merchant vessels sunk this month were either sailing alone or stragglers from convoys.
Axis Loss Summary - 1 Italian U-boat.
Summary of January 1941
Battle of the Atlantic - For the next few months the U-boat’s ‘Happy Time’ continued in the Western Approaches against the poorly defended convoys. However these wwere unhappy times for U-Boat arm now. Bad weather in January and February fortunately kept the level of Allied merchant vessel sinkings down. Approximately 22 U-boats were operational out of the 60 in commission, and long-range aircraft from Lufrtwaffe Specialised Maritme Gruppe 40 , including the Focke Wulf-200 Condors began roaming the waters off Ireland spotting for U-boats and sinking ships. But due to breakdown in wireless communications , bad weather and breakdowns in a long command and control chain , these sighting reports were relayed to U-Boats at sea too late.
Monthly Loss Summary
- 59 British, Allied and neutral ships of 273,000 tons in the Atlantic from all causes
- 1 Italian U-boat.
FEBRUARY 1941
In the North Atlantic, Admiral Dönitz’s son-in-law Captain Günter Hessler in the new IXB U-107 found convoy OB 279 on February 3. After flashing an alert, Hessler attacked, sinking a 4,700-ton freighter, then shadowed during the day. Doenitz relayed the report and ordered six other U-Boats to converge on the convoy. Still shadowing, on the following evening Hessler sank a second ship of 5,000 tons. No other U-Boats found the convoy, but while searching for it, Salmann in U-52 and Moehle in U-123 came across the inbound SC20, from which they sank one ship each, as did Hessler in U-107, responding to their reports. Korth in U-93 polished off another ship from this convoy with his deck gun, a 2,700-tonner which had been damaged by a Fw-200 Condor from Norway.
German Heavy Warships - At the beginning of the month, German heavy cruiser “Admiral Hipper” sailed from Brest.
On 9th February Convoy HG-53 en route from Gibraltar to Britain was discovered by U-37. In three days U-37 with hit and run assaults , topedoed and sunk three ships totalling 16.000 tons and then called for Luftwaffe Specialised Maritime Gruppe 40 based on Bordeux to attack on located convoy. Luftwaffe Fw-200 Condors from Bordeux , sunk five more ships totalling 20.000 tons. (this was the first and one of few cooperated German Navy Luftwaffe operations during entire war) Meanwhile on the 12th February , German heavy cruiser Admiral Hipper far to the west of Gibraltar, she sank seven ships from slow unescorted convoy SLS64 bound for Britain from Sierra Leone. But afterwards “Admiral Hipper” suffered severe engine malfunction (engines of German capital ships had severe design flaws malfunctioning especially in high seas) returning to Brest, in March she headed back to Germany via the Denmark Strait and took no further part in independent commerce raiding.
On the **8th February , battlecruisers “Scharnhorst” and “Gneisenau” sighted convoy HX106 escorted by the lone battleship “Ramillies” south of Greenland, but declined to attack in case of possible damage. Two weeks later, five unescorted ships were sunk east of Newfoundland by these two German battlecruisers, before they headed for the Sierra Leone routes. Meanwhile pocket battleship “Admiral Scheer” in the Indian Ocean operated successfully off Madagascar before preparing to return to Germany.
**22nd February - Italian submarine “MARCELLO” was believed sunk to the west of the Hebrides by ex-US destroyer HMS Montgomery and other escorts of Liverpool-out convoy OB287. This convoy was reported by Fw-200 Condors on 21st February. Condors then sank two merchant ships and damaged four other merchantmen. On 22 February , U-73 discovered OB287 and reported its position. Next day five U-Boats and Italian submarine BIANCI formed the wolfpack and attacked thoughout the night , sinking eight ships totalling 43.000 tons. But meantime newly arrived Italian submarine MARCELLO was sunk by depth charges of HMS Montgomery.
On 24 Captain Erich Topps U-557 found convoy OB289 off Iceland but all torpedoes he launched either , missed , misfired or malfunctioned. From his radio report U-97 also arrived to intercept thgis convoy but he could sink only three ships from it before retreating and losing the convoy. On 25th February Gunther Prien’s U-47 discovered convoy OB-290 off Ireland and alerted U-Boat command in Kerneval France and Lufrtagge Gruppe 40 in Norway. U-47 sunk four merchants from this convoy , newly arrived Italian submarine BIANCHI sunk one more ship. But real damage was done by FW-Condors of Gruppe 40 which sunk seven ships. Altogether OB290 lost 12 ships totalling 55.000 tons. After that no more U-boat attacks were made to this or other convoys this month.
Despite heavy Allied merchant vessel casaulties again this month , if you look carefully there is a noticible decrease in merchant sinkings by U-Boats and and reduced interception of Allied convoys by U-Boat arm , most of these sinkings are lone sailing merchant vessels or sunk by surface raider and Luftwaffe. The reasons of decreasing U-Boat combat effectiveness are below.
Summary of February 1941
Battle of the Atlantic - Adm Sir Percy Noble took over as Commander-in-Chief, Western Approaches, just as the command movesd from Plymouth to Liverpool.
Monthly Loss Summary
- 69 British, Allied and neutral ships of 317,000 tons in the Atlantic from all causes
- 1 Italian U-boat.
MARCH 1941
**7th/8th March - With better weather the spring U-boat offensive started and 41 ships of 243,000 tons sunk. However, in the space of a few days they suffered their first major defeat at the hands of the escorts and lost five submarines (1-5) in the month including elimination of three German U-Boat aces. From then on, escort versus wolf-pack battles predominated in the North Atlantic. Attacking Liverpool-out convoy OB293, the first sinking was “U-70” (1) by corvettes HMS Arbutus and HMS Camellia on the 7th March 1941 . Continuing the hunt, next to go was “U-47” (2) (Cdr Prien who sank battleship “Royal Oak” in Scapa Flow) to destroyer HMS Wolverine on the 8th March (though some naval historians disagree on that , neverthless U-47 disappeared after aproaching convoy OB239. Its cause of demise is either due to depth charge attack of HMS Wolverine or explosion of her torpedoes accidently in tubes/diving accident )
On March 1 after dark, Erich Topp in the VIIC U-552 ran into the inbound convoy HX 109, which was approaching the coast of Scotland, leaving little sea room. Topp broadcast an alarm and with his last three internal torpedoes sank a 12,000-ton British tanker, Cadillac, his first success in U-552. A new VIIC, U-70, commanded by Joachim Matz, age twenty-seven, from the duck U-59, merely eight days out of Helgoland, arrived and set up on the Cadillac, only to see Topp blow it up in his face. Gerd Schreiber came up in the VIIC U-95 and sank two ships for 11,100 tons. Reinhard Hardegen in the duck U-147 sank a 4,800-ton Norwegian freighter, then returned to Germany. One of two Condors staging from Norway reported an outbound convoy and attacked on the morning of March 2. Dönitz directed six of the seven oceangoing boats in the hunting grounds to form a north-south patrol line west of Rockall Bank. While the boats were moving into position through a dense fog on March 3, Condors scoured the probable course of the convoy but saw nothing. Nor did the near-blind boats.
After a hurried analysis of this failed operation, Dönitz ordered a drastic—and “lamentable”—change in Condor operations. Concluding that when Condors openly attacked a convoy they forced it to make a drastic alteration in course to avoid the converging U-boats, Dönitz barred Condors from attacking convoys. Henceforth they were only to spot and report convoys and make every possible effort to remain undetected, restrictions that hardly pleased the Condor crews. The next day, March 4, a Condor reported another outbound convoy. It was not clear from the position report whether this was the same outbound convoy or a new one or if the position report was accurate. Nonetheless, Dönitz redeployed the six boats in a patrol line farther west, adding to it the U-A, commanded by Hans Eckermann, en route from Germany to Lorient to stage to West African waters. After the line was in place, on March 5, Gerd Schreiber in U-95, in the center of the line, inexplicably broke radio silence to report his accumulated sinkings. Assuming the British had located U-95’s position by radio report tracking and would alter the convoy’s course to avoid him—as well as the whole patrol line—Dönitz logged that Schreiber had made “an extremely clumsy mistake.” Dönitz may have been correct; the convoy got away. The failure to intercept either of these two outbound convoys led to a more detailed analysis of Condor/U-boat operations.
The study revealed that in two months the U-boats had benefited only once (February 19–20) from Condor convoy reports. Almost without exception, Condor reports were incorrect as to the positions and courses of the convoys. Besides that, it took too long to redeploy the boats. By the time they reached the most likely interception line based on the reported convoy course (whether accurate or not), the report was twenty-four hours old and not reliable. Dönitz therefore directed that until better means of submarine/aircraft position reporting and cooperation could be found, “no more U-boat operations” were to be “undertaken on aircraft reports.” Condors were to continue patrolling and reporting convoys for the benefit of all German forces and they were again allowed to attack convoys on sight.
On March 6, Dönitz redeployed the boats. Five VIIs formed a north-south patrol line west of Rockall Bank, and the U-A went west to relieve U-97 as the weather reporter. The patrol line had only just formed when Prien in U-47 encountered and reported an outbound convoy. He shadowed and broadcast beacon signals to bring up the other boats. Dönitz directed three other boats of the patrol line—U-37 (Clausen), U-70 (Matz), U-99 (Kretschmer)—and also the westbound U-A to converge on Prien’s signals. This was convoy OB 293, escorted by two destroyers, HMS Wolverine and HMS Verity, and two corvettes, HMS Arbutus and HMS Camellia. Prien in U-47 and Kretschmer in U-99 met in moderate, misty seas at 6:00 P.M. Talking by megaphone across the water, they planned a joint attack on the convoy. As they were talking, the two destroyers—both with Type 286M radar—loomed out of the mist: HMS Wolverine, commanded by James M. Rowland, and HMS Verity.
Patrolling ahead of the convoy, the destroyers caught Prien and Kretschmer by surprise, forcing both U-boats to crash-dive. The destroyers found Prien and worked him over with depth charges. Kretschmer went deep and slipped away. Later in the night, both boats surfaced. Meanwhile, Joachim Matz in the new U-70 arrived, taking up position in the dark ahead of the convoy. Matz had been in the Atlantic all of two weeks and had yet to fire a torpedo. At 0430 hours on March 7, he attacked, firing all four bow torpedoes at four different ships. He later claimed that he had hit and sunk all four (for 35,500 tons) but in reality, he had hit but only damaged the 6,400-ton British freighter Delilian and possibly the 6,600-ton British tanker Athelbeach. Ten minutes later, Prien, who was low on torpedoes, radioed Dönitz an updated position report, then attacked, choosing the largest ship in the convoy, the 20,640-ton Norwegian whale-factory ship, Terje Viken, converted to a tanker. Prien hit her with two torpedoes, but she was in ballast and thus very hard to sink. Although damaged, she sailed on. Having reloaded his four bow tubes, at 0600 Matz came in for a second attack. He saw the damaged Terje Viken and fired three torpedoes at her, but all three missed. He was on the point of firing his fourth bow tube when another boat hit the factory ship with one torpedo. That shot came from Kretschmer in U-99. Kretschmer then fired one torpedo at another ship, but missed. Swinging about, he shot three torpedoes at the possibly damaged tanker Athelbeach. Kretschmer fired another torpedo to sink the tanker.
The four escorts, under tactical command of James Rowland in the destroyer HMS Wolverine, reacted aggressively. While the convoy was making a sharp evasive turn to port, they lit up the area with star shells and commenced hunting U-47, U-70, and U-99, all of which were in close proximity. The corvette HMS Arbutus got the first sonar contact at 0448 hours and dropped depth charges, calling up the other corvette, Camellia. The destroyers Wolverine and Verity spotted U-boats and drove them under, dropping depth charges. U-70 under command of Captain Matz while trying to get a better angle , was rammed by Dutch tanker Mijdrect and badly damaged. Then corvette HMS Arbutus arrived and doggedly pursued U-70, firing five salvos of six charges over the next three hours. In all, U-70 took fifty-four charges. The last three attacks by Arbutus fatally wrecked U-70. She flooded aft and went out of control, assuming a 45-degree up-angle. Matz crammed all available men into the bow compartment, but to no avail. The boat slipped down by the stern to 656 feet. Unable to regain control, Matz blew all ballast tanks with his last bit of high-pressure air and surfaced to scuttle. Seeing her, Arbutus came in to ram, firing her 4″ deck gun and other weapons. When Matz opened the conning-tower hatch, the pressure inside the boat was so great that it blew him and five other men straight up into the smashed bridge. Seeing the U-70 crew jumping into the water, Arbutus veered off and dropped two life rafts. With hatches and sea cocks open, the U-70 plunged down by the bow and sank. Arbutus fished Matz and twenty-five other men from the water. Twenty Germans died in the sinking.
Nothing more was ever heard from Prien and U-47. That night Prien—as well as Matz—failed to respond to requests from Dönitz for position and sinking reports. Same day a few hours later HMS Wolverine located and attacked a submerged U-Boat with a highly accurate depth charge attack (wreckage from a sunk U-Boat was sen off surface) but it is unknown whether this was Prien’s U-47 which was destroyed or older UA which was badly damaged but got away from pursuit of escorts. Whatever the case, the four escorts of convoy OB 293 deserved highest praise and awards. Their aggressive U-boat attacks had not only fended off Germany’s two foremost U-boat aces with slight losses in ships* but also had sunk one of them, as well as the U-70, and had nearly sunk U-A. No other escort team had ever done as well. Moreover, U-47 and U-70 were the first confirmed U-boat kills by British forces since the loss of U-31 on November 2, ending a humiliating dry spell of more than four months.
German Heavy Ships - battlecruisers “Scharnhorst” and “Gneisenau” were sighted by aircraft of battleship HMS Malaya" escorting convoy SL67 off the Cape Verde Islands. The German ships realising they were discovered (and under strict orders not to give battle with capital ships of Royal Navy) returned to the Newfoundland area and on the 15th and 16th sank or captured 16 unescorted ships on this shipping route. They returned to Brest on the 22 March, having accounted for 22 ships of 116,000 tons, but never again took part successfully in commerce raiding.
17th March - Germany lost two more U-boat aces during operations against Halifax/UK convoy HX112. “U-99” (3) (Lt-Cdr Kretschmer) and “U-100” (4) (Lt-Cdr Schepke) were sunk by the 5th Escort Group commanded by Cdr Macintyre. Royal Navy destroyers HMS Vanoc and HMS Walker (commanded by Captain Donald McIntrye , one pof the leading U-Boat hunters of the war and author of several books about naval warfare after thwe war) were mainly responsible.
20th March - Following her earlier sighting of the “Scharnhorst” and “Gneisenau”, “Malaya” was now sailing with convoy SL68 off the west coast of Africa. Torpedoed and damaged by “U-106”, she became the first British ship repaired in the United States under Lend-Lease arrangements. The convoy lost seven merchantmen to the U-boats.
23rd March - The fifth U-boat loss of the month was “U-551” (5) to Royal Navy armed trawler HMS Visenda. All five U-boat sinkings took place to the south of Iceland, the first German casualties since November 1940 - four months earlier.
Summary of March 1941
Battle of the Atlantic - On 6th March 1941, faced with the mortal threat of the German U-boat and aircraft offensive in the Atlantic, Winston Churchill issued his famous Battle of the Atlantic directive. Catapult armed merchantmen (CAM) were to be fitted out, merchant ships equipped with AA weapons as a first priority, and more Coastal Command squadrons formed and fitted with radar. Port and dockyard congestion was to be dealt with and the defence of ports greatly improved. These and numerous other matters were to be dealt with as a matter of the very highest priority. The survival of Britain depended on them. Overall direction was to be exercised by a Battle of the Atlantic Committee chaired by the Prime Minister himself.
Monthly Loss Summary
- 63 British, Allied and neutral ships of 365,000 tons in the Atlantic from all causes
- 5 German U-boats-including three of the most experienced commanders.
Causes of Decreasing U-Boat sinkings (which was temporarily offset by German surface raiders )
According to David Mason (U-Boat the Secret Menace 1968) , after running wild , sinking a huge tonnage from rather defenceless Allied convoys during last four months of 1940 , a decrease of combat effectiveness and performance of German Navy U-Boat arm was inevitable. A series of related or unrelated factors caused this outcome : Despite post war image of efficient U-Boat arm with countless submarines , the truth was ironically , when February 1941 started German Navy still had almost same number of submarines when it started the war in September 1939 (17 moths ago) : Only 58 U-Boats. (though all of them were built as ocean going long range Type VII or Type IX submarines now) For almost one and half years , the number of U-Boats in German Navy ready for combat operations remained same ! German Navy during this time constructed only enough U-Boats to compansate its losses so far. Only after mid February 1941 , number of U-Boats began to increase with accelerated construction programme and increasing number of naval recruits/volunteers for German Navy. (by May 1941 there would be 95 U-Boats available for German Navy) But disadvantage of that was newly trained crews (second generation of U-Boat crews) did not always had professionalism of first generation of U-Boat captains or crews (among a handful of them-U-Boat aces were responsible most of Alllied merchant sinkings) While number of U-Boats began to increase avalable for Admiral Doenitz to wage his tonnage war against Britain , number of ships sunk per U-Boats (avarage sinking each submarine accomoplished) would decrease due to lack of combat experience among new crews and some deficiencies in their training due to accelerated construction programme and still ongoing torpedo problems in U-Boats. (several torpedoes they launched were still non functional and did not detonate. After Norwegian Campaign , Doenitz put up a Torpedo Committe that rectified most of torpedo malfunction problems but not all of them) As a result inexperienced U-Boat captains who misidentified the vessels they targetted and just like over zealous fighter pilots they exagerrated number and tonnage of Allied merchants they hit and sunk , creating inflated Allied merchant loss figures and confusion. Also training of new U-Boat crews were getting quite delayed due to ice forming in Baltic Sea (main German Navy training ground) By February 1941 , of 58 U-Boats still present , one third of them were at their ports for maintenance , rest , supply , other one third were in training duties for new crews in Batic Sea , only 20 U-Boats were still present at combat patrol aross the whole Atlantic trying to bring down entire British war effort.
Also with winter season came in full , U-Boats on patrol couldn’t detect enemy vessels or convoys efficiently. Due to severe storms in Atlantic during this season that shaked surfaced U-Boats (therefore they had to stay submerged most of the time except battey recharge) , threw down their observers in conning towers and ruining their visibility and prevented their communication or sighting of enemy. According to Clay Blair (Hitler’s U-Boat War 2000) : By December 1940, the oceangoing boats available for patrol had shrunk to six, the lowest number of any month in 1940. Four sailed from Lorient and two, the VIIC U-96 and the IXB U-105, embarked from Germany on maiden patrols. These six boats, as well as the November boats still on patrol, confronted raging westerly gales, the onset of a brutal and frigid winter, which was to be even worse than that of 1939–1940. The parade of gales churned up awesome grey seas which lifted the boats to giddy crests, then dropped them into terrifying troughs. The boats and pitched and shuddered, slewing wildly to port and starboard and rolling to impossible angles. The winds flung biting cold spray—or hail and sleet—at the men on the bridge. From time to time huge waves broke over the bridge, submerging the men and bashing them about, putting human lungs and safety belts to the test. More often than not, visibility was nil. Conditions below were pure hell, like living inside a tumbling, wet barrel. It was not possible to cook or serve meals. Few cared. Even the oldest salts felt queasy and disoriented.
Blair, Clay. Hitler’s U-Boat War: The Hunters 1939-1942 (Volume 1) .
But main factor in decrease of U-Boats efficiency was due to enemy activity. After heavy merchant losses in convoys during last months of previous year , British Admiralty put all of its resources available to anti submarine warfare and convoy protection. In the beginning of March 1941 , Prime Minister Winston Churchill called out ongoing struggle as Battle of Atlantic and ordered all resources in all arms to combat U-Boat and Kriegsmarine raider threat. Entire Western Approaches Command of Royal Navy was carried from Plymouth to Derby House Liverpool on February 1941 and on 7th February , highly efficient Admiral Sir Percy-Noble took command of it. Luckily , due to invasion threat to British Isles passed away , more and more small or medium sized convoy escort vessels were available for escort duty. Previously these small tonnage destroyers , sloops , corvettes and trawlers were tied up in narrow waters of North Sea and English Channel against German invasion of Britain that never came. Now that threat was over all these escort ships (by February 1941 appox 300 of them of all size and tonnage more or less suitable for crossing Atlantic ) were available for convoy escort duty.
On top of that British Admiralty began to acquire more and more escort vessels due to vastly increased escort vessel and destroyer construction programme off shipyards with well trained crews graduated from a very through school and live course at Anti-Submarine School off Hebrides (here under command of tough and uncompramising Rear Admiral G. Stephenson , Royal Navy and Commonwealth crews were trained with live combat drill procedures as much as possible. Commander of RN Western Approaches Admiral Percy Noble was determined every escort vessel crew should go from this school and utterly drilled trained and prepared for combat in open seas) New model light but long range ocean crossing Flower class corvettes and new V and H class destroyers designed for anti submarine warfare were entering Royal Navy service. This way first Escort Groups came into being in February 1941. These groups were to be composed of ships, more or less permanently teamed up and assigned as a single entity to convoys. The Admiralty believed that when so permanently organized and trained, the groups could better protect convoys—and kill U-boats—than randomly assigned single vessels. Fostered by Percy Noble, and trained by Stephenson, there were soon a dozen such groups, each consisting on paper of ten destroyers, sloops, or corvettes, of which six to eight were maintained at readiness to sail. The performance of the groups, manned almost solely by wartime conscripts or volunteers, was ragged at first and never perfect, but gradually became quite proficient. All Americans who visited British military agencies in 1941 were impressed by the degree of unification that had been achieved in the Battle of the Atlantic. From the War Cabinet to the Battle of the Atlantic Committee to the Admiralty and the Air Ministry, to Bletchley Park and the OIC and Derby House, all hands worked with an extraordinary singleness of purpose.
As a result , even an experienced U-Boat wolfpack with veteren submarine crews like aces (Kretchmer , Schepke) attacked a convoy such as HX-112 off Iceland on 7 March 1941 , it suffered heavy casaulties (Schepke’s U-100 was sunk by destroyer HMS Vanoc and Kretscmers’s U-Boat was sunk by destroyer HMS Walker , latter U-Boat ace was captured with most of his crew to spend rest of the war as a POW) despite sinking several merchants again. With loss off these few but highly lethal killer U-Boat ace captains and veteran crews , German Navy U-Boat arm average sinkings per submarine dropped as convoy escort protection screens grew more and more strong and even worse gor U-Boats , most of these new escort vessels were equipped with radars (Type 210s) and radio signal tracking devices (Huff Duff) as well as Asdic and passive hydrophones .
Even a bigger disadvantage for U-Boats was British technological and intelligence leaps utilised by Royal Navy Western Approaches Command and Royal Navy/RAF. British Signals Intelligence (Y-Service) and Signals tracking were becoming more and more efficient in tracking U-Boat wiresless reports to U-Boat HQ on Kerneval France , triangulating and finding locations of U-Boats which were constantly broadcasting in Atlantic. German Navy did not have a proper dicipline in keeping length of radio broadcasts and Admiral Doenitz himself instructing his captains on patrol to send him reports constantly especially about discovered convoys to form wolfpacks for attacks. As a result , U-Boats locations discovered themselves by Royal Navy and even if they were not tracked , hunted attacked instantly by British anti submarine forces , Royal Navy Western Approaches Command in Liverpool with fresh intelligence about location of U-Boat patrols at hand (Submarine Tracking Room run by Naval Intelligence Division of Royal Navy was evaluating all intelligence gathered from every resource and updating , catagorising them. Here under brilliant data evaluation and command of Lt. Commander Rodger Winn-later promoted to commander rank , did I tell you that he was also paralytic in his legs ?- , Royal Navy Western Approaches Command tracked U-Boat movements as much as possible) , usually intervened just in time to change route of a hapless convoy away from an U-Boat patrol line. As a result U-Boats remained at their positions , finding no targets and returning their home bases empty handed to replenish fuel and supplies and to rest their crews. Even worse though , due to several Enigma “pirches” (capture of Enigma machines and codes , rotors ,materials etc) during first half of 1941 , Goverment Decypher School in Bletchley Park , began to decode and read coded German Navy messages and broadcasts in May 1941 and turned intelligence war further in favour of British Admiralty.
On top of that after conclusion of Battle of Britain , RAF Coastal Command under capable command of Vice Air Marshall John Slessor , began to expand with acquiring more aircraft and personnel and entered under command of Royal Navy. With more air patrols covering North Sea , east and west of Iceland , from Orknes , Hebrides and Scotland and from Southern England and much closer coperation of RAF Coastal Command with Royal Navy (RAF Coastal Command HQ was also moved to newly created Royal Navy Western Approaches Command in Derby House Liverpool and two commands were almost merged , creating a highly efficient cooperation) , due to frequent Coastal Command air patrols , U-Boats were being driven off further and further away from coastal and narrow waters towards open Atlantic to find their prey. Easy hunting of single sailing ships close to British held shores was mostly over. At the other hand except two squadrons of Fw-200 Condor anti shipping aircraft (Gruppe 40 based on Bordeux and Norway) that were still directly under Luftwaffe command (Reichsmarshall Hermann Goering and other Luftwaffe chiefs were quite reluctant to share their resources with other arms due to interservice rivalries. Due to no direct naval command these aircraft were slow to deploy after discovery of a target since deployment and sortie orders coming from German Navy instead of Luftwaffe which was a different arm and command control authority was muddled between Germany Navy and Luftwaffe. Their comnmander in chiefs were not on speaking terms if not openly hostile especially Goering) German Navy had no air support and suffering from this.
Actually during this period between January-April 1941 British Admiralty was more concerned about German surface raiders like Scharnhorst and Gneisenau (that sunk 22 ships of 122.000 tons between February - March 1941 ) , Admiral Hipper , Admiral Scheer and German auxilary cruisers off far seas that were causing havoc. (not to mention big and modern German warships Bismark and Tirpitz were about to be operational) Luftwaffe Fw-200 Condor attacks were also another serious problem but Western Aprroaches Command and Royal Navy began to find fast solutions for against that like establishing RAF Coastal Command fighter patrols over convoys in range and putting CAM vessels (catapult fighter launching merchants that could launch one fighter aircraft to air) to convoys and increasing anti aircraft armaments in merchant and escort vessels. Before years end also , newly constructed escort carriers which were able to carry multiple anti submarine and fighter aircraft against “Condor scourge” would begin to escort convoys.