** World War II naval campaigns -- the Atlantic phase 2

World War II Naval Campaign: The Atlantic -- Second Phase (1942-45)

Figure 1.--Here U.S. Coastguardsmen on the cutter 'Spencer' are depth charging the U-175 (1943). British scientists worked out early on that escort vessels equipped with basic equioment should depth charge U-boats immediately because once the Germans were submerged for only a short period, the chances of scoring a hit were limited. This was one of many instance that the scientists took on entrenched military thinking. [Budiansky] By 1943 the Allies had perfected ASW tactics and developed improved equiopment that ebabled them to successfully engage U-boats under water that were attempting to elude Allied escorts.

After the disasters before Moscow (1941) Stalingrad (1942), and Tunisia (1943), tthe NAZi war effort was clearly failing. To add to their woes, the American ahad joined the British strategic bombing campaign. The one bright spot in 1943 was the North Atlantic where German U-boats achieved great successes in early 1943. And the North Atlantic was a critical battlefield of the War. Success here would mean not only that the Americans could not enter the war in Europe, but that Britain could not continue the War. It would have meant the end if the strategic bombing campaign and meant that there would have been no D-Day invasion. The Allies were, however, making great advances in anti-sunmarine warfare and code breaking. Besides the Americans and British, the Canadians played a key role in the Battle of the Atlantic. The decisice encounters came in May 1943. German U-boat losses were so great that Admiral Donenitz was forced to pull the U-boats out of the North Atlantic. The Allies made service in U-boats one of the most deadly assignments in World War II. Free of the U-boat menance, a torrent of American soldiers abd airmen and unprecedent quantities of arms and supplies from the Arsenal of Democracy headed for Europe.

U-boat Pens

Finding a U-boat at sea was a difficult undertaking, especially at the beginning iof the War when Allies ASW operations were still very ineffective and escorts were in short supply. It soon dawned on the Allies that it was mucg easier to find and attack the U-boats when they docked for servicing and resupply. This was a process that took some time as the Germans had an elavorate servicing process because the U.boats operated in such as hostile enviriment. The Germans made no real effort to harden U-boat facilities before the War. Admiral Dönitz's U-bpat service was very small and Hitler had no real interest in naval affairs only showed an interest in big-gun battle ships. This began to change after the War began for a variety of reasons. First, Dönitz's U-boats began reporting considerable success, attracting Hitler's attention. Second, Germany's surface ships took a beating. The sinking of Bismarck appears to have ended Hitler's infatuation with battleships. Third, Britain's survival in the Battle of Britain and decision to build a massive bomber force meant that Dönitz's growing U-boat fleet was vulnerable to air attack. The Germans as a result began a massive program of building protected submarine pens all along the Baltic and North Sea coasts. This effort might have focused on Norway which the Germans invaded (April 1940). The subsequent all of France, howevr, provided much more valiable Atlantic coast ports. As a result this becane the focus of German construction. The most massive pens went up in L'Orient where Dönitz set up his headquarters. Three bunkers (Keroman I, II and III) were built there. The Scorff bunker and two Dom (cathedral) bunkers were also built. They were massive bomb proof constrctions that even the RAF Tall Boys could not penetrate. Instead the British began attackking the the towns and rail lines keading into to the pens. And as thee Allies aur power grew, they began attacking the U-boat bases in the Reich which the Germans were slower to harden. We are not sure why the RAF did not target the French U-boat pens while they still were under condtruction. Two more were planned, but never built as the war went against the Germans.

German Heroes

NAZI propaganda presented U-boat men as great heroes in the German people. Goebbels' propagandists called the captains Knights of the Deep". Some of the leading captains were known by name to the public. Their achievents were chronicled in the movie news reels and the press. And in part because of Admiral Dönitz they became the most Nazified of the military services outside of the Waffen-SS. They would eventually earn theior hero status. Serving on a German U-boat by 1943 became the most dangerous duty in the German war effort. Some of the most important captains, men like Günther Prien, began disappearing as early as 1941. A shockingly small number of U-boat crew members survived the War, including two of Dönitz's sons.

Admiral Dönitz

The success of Germany's U-boat camapign was in large measure due to tactics developed by Admiral Dönitz, a World War I U-boat commander and ardent NAZI. It was Dönitz who conceived of the wolf pack and honed the tactics involved. He made, however, major mitakes. The major one was pitting the young men of the U-boat service including his sons against the massive industrial and technical resources of Britain and the United States. THat said he came frightingly close to deivering victory in the North Atlantic to his Führer. Dönitz was a master technician, but he was often dismissive of technology. He thought SONAR was overated. Here he was proved correct, at least early in the War when sonar technology was still fairly primitive. After World War I, limited efforts were made to improve sonar. He planned a strategy involving surface attacks, often at night, in which SONAR was of little use. In the early years of the War, these tactics proved highly successful against the lightly defended British convoys. The Royal Navy had been down-sized after World War I and was woefully short of escort craft, especially before the U.S. Navy joined the effort. The World War I destroyers provided by America helped, but many more escorts and and better ASW equipment was needed. Donenitz badly miscalulated the importance of both RADAR and SONAR. And the ability of the Allies to extend air cover. The Allies in 1942 slowly improved their equipment and perfected tactics. In addition, the long-range aircraft and escort carriers churned out by American shipyards gradually increased aerial cover for the convoys. Another serious miscalculation by Dönitz was the excessive use of radio communication. Dönintz believed in maintaining very close control over his U-boats. This was important, especially when he had intelligence about the location of the convoys. And cracking Britiah Naval Cipher 3 gave him invaluable intelligence. The level of radio traffic involved helped the Allies locate the U-boats through radio directional information. It also provided Bletchely Park the quantity of intercepts needed to crack Shark--the naval Enigma key Dönitz used to direct his U-boats. Dönitz like other German commanders did not believe the Allies could crack the Enigma cyphers. He was, however, appropritely cautious and insisted that the Kriegsmarine Enigma machines be made more secure than the standard Enigma machine, among other matters adding a fourth rotor. And the naval operators were drilled to be more more careful than those of the other services. As a result, The Kriegsmarine Enigmas, especially Shark, proved the most fomidable challeng for the British code breakers at Bletchely Park.

Air Component

The Battle of the Atlantic was of course a naval campaign, but there was an important air compnent to it. The British and susequently the Americans had coastal patrols to cover convoys. And air cover from islands such as Bermuda and Iceland covered ocean areas as well. The Destroyers for Bases deal gave the U.S. Navy additional facilities for ocean patrol. Allies like Brazil were also important. The Brazilians and merican personnel in Brazil heped close the Atlabntic narrows. Long range American Catalinas and B-24 Liberators played important roles. The British got Catalinas even before America entered the War. It was an American Catalina with Americans part of the crew that found Bismarck. The U.S, Navy also used blimps. There was a substantial mid-ocean gap through 1943 where the convoys had no air cover. The Kriegsmarine after the fall of France (June 1940) rushed to open U-boat bases in French ports, including Accueil, Bordeaux, Brest, La Rochelle, L'Orient, and St. Nazaire. This greatly increased the striking power of the still fairly small U-boat fleet at the time. Operating from French ports meant that the lengthy trip back to German/Norwegian ports was no longer necessary. And by 1941 the number of U-boats was increasing substantially. The Luftwaffe attempted to support the U-boats ny attacking convoys and ports. Here they had some success at attacking ports, but convoy attacks were limited by the small number of long-range bombers and British counter-measures like ship launched fighters. The Luftwaffe was more successful in attacks on the Arctic convoys. Germany did nit have the industrial potential to build long-rangge bombers to attack the convoys and Brutish ports in force. In contrast the Allies, especially the United States, did have the industrial caoacity to build the aircraft needed for the Battle of the Atlantic. The Allies could not cover convoys with fleet carriers, but the innovation of jeep (small) carriers helped provide air cover for the convoys. Technical advances in radar and ASW weapons forrced Dönitz to withdraw his U-boats from the Atantic (July 1943). The U-boats were not completely withdrawn because a small number of U-boats forced the Allies to devote considerable resources to protecting the convoys. As the Luftwaffe was shifted east for Barbarossa and the Americans joined the British in the air war, the U-boat bases in France came under extensive attack. The U-boat pens thenmselves were hardened, but the rail lines leading to them were not. These bases despite the heavy bombardment continued to function until the D-Day landings and Allied breakout forced the Germans to withdraw (July 1944).

German Code Breaking

A great deal has been written about the British Ultra cracking of the German enigma codes and the the impact on the War, especially the campaign against the U-boats in the North Atlantic. Less well known are the Germans code breaking efforts. The Germans suceeded in breaking the British naval convoy code. The Germans had several code breaking operation. By far the most competent was the Kriegsmarine signal intelligence agency--Beobachtungsdienst (surveillance service, B-Dienst). The Royal Navy inroduced a new code--Naval Cipher 3 (November 1941). The Germns cracked it in 3 monts (February 1942). The Germany by the summer of 1942 were reading up to 80 percent of some codes, including the all important Naval Cipher 3 with convoy information. The Atlantic is a big place and The German U-boats especially in the first years of the War could not wage an effective commerce war without intelligence about the convoys. Cracking Nacal Cipher 3 gave Dönitz the priceless intelligence he needed. The British were using a rather basic code. Surpringly given the fact that they were breaking a far more difficult German code, they did not seem to believe that they neded a more challenging code. It was the most serious Allied security lapse of World War II on a par with the cracking of the German and Japanese codes. Ironically the German achievement while enabling the U-bots to savage quite a number of convoys led them to believe that their own codes were secure. It was clear from reading the Brirish traffic that they were not reading Shark, the German naval Enigma key used by Adminral Dönitz to direct his U-boats. One of the great coincided of the Bttle of the Atlnioc is that Bletchley Park began breaking into Shark just as the Germans were losing access to Naval Cipher 2. It is at this time that the Admiralty began to take action. Decrypted Ultra intercepts suggested that the Germans had broken the British code. The Ulltra team reported this to the Admiralty (July 1942). Almost inconceivably, the Royal Navy continued to use the code for 10 months at imense cost. It is unclear how this could have happened, but the same institutional forces were at play that led the Germans to conclude that their vaunted Enigma cyphers were secure. The Ultra project was a closely guarded secret and thus reports that their code had been broken did not explain how this conclusion had been reached. Nor was the now legendary reputation of Bletchey Park well established in 1941. Changing a code is a complicated and costly process. Apparently Admiralty officials were reluctant to admit that there code was so easily cracked and to go to the complicated process of introducing a new code. As a result, the Royal Navy continued used Naval Cipher 3 for 10 months after being informned that the Germans had cracked it. In addition the Germans at the beginning of the War used information available from commercial shippers, especially insurance data. The Germans also tapped a trans-Atlantic telephone cable. Over hearing a conversation between Roosevelt and Churchill helped them act quickly to prevent the Allies from seizing southern Italy and Rome in 1943.

Expanded U-boat Campaign (1942)

With the expanded U-boat construction, Dönitz finally ad the force he needed to wage a major U-boat campaign. After Operation Drumbeat saving shipping off the U.S. tlantic coast, Dönitz moved the U-boat campaign into the mid-Atlantic Gap beyond the reach of Allied aerial patrols. Given the success of the U-boats, the Germans stepped up production even further. The principal German tacic was the Wolf pack which was often a griuping of 10-12 Uboats, but some were as large as 50 U-boats. The German effort was conducted from a command center in Paris. The Germans would establish a kind of picketline of U-boats along the convoy routes. Then when a convoy was detected Doenitz in Paris would give orders for each U-boat to converge for a coordinated attack. The U-boat which first spotted a convoy would not attack, but instead shadow it so that it could continue to relay its position. The U-boats were fast on the surface, about 17 knots. U-boats would find the convoys visually by smoke and ten then they could see the tasts and funnels submerge. One they could see the bridge than the convoy vessels could see he conning tower of the U-boat. The stategy would be for a Wolf Pack to draw off the escorts and then attack from all sides. Some U-boats even entered among the convoy ships to attack from within. The Germany developed the Leut torpedo which could zig zag, increasing the chances of hitting a vessel within a convoy. The Germans also itroduced a new type of U-boat, the Milk Cow which could carry 700 tons of fuel and supplies which could resupply U-boats at sea. Even after America entered the War, U-boat sinkings of merchants vessels increased. The tonnage sunk set a new record in 1942. The Germans by the beginning of 1943 had a U-boat fleet of 393 vessels, a force Doenitz believed could bring victory. Not only was the fleet greatly expanded, they were improved types capable of operating as far as the U.S. coast, and they had elaborate bases in French ports, greatly facilitating Atlantic operastions. Total sinkings by the end of 1941 had reached 1,094 ships resulting in the loss of over 10,000 seamen.

The Game

The Royal Navy sent its commanders back to school and to play 'The Game". Classes presented finally honed instructions on how escort commanders should deal with U-boat attacks. And details about technological advances abd equipment being provided the escorts. They were given command of escorts protecting a convoy. Wrens would deliver scenarios and condiutions the commanders woould beve to make decisions on how to best deplu their escorts to pary whatever German attack was presented in the game senrio presnted to them. It forced them to comfromt the difficult decesions required in atual combat.

End Game (1943)

Tipping Point (January-February 1943)

The primary tactic of the Royal Navy with its limited escorts was to avoid the U-boats. And with the small number of U-boats available to Dönitz, this and the convoy system proved the most effective tactics. The Submarine Tracking System was this the heart of the Royal Navy's effort. Because Shark, the Enigma key used by Dönitz provedso impenetrable, until 1043, they had to rely on radio directional operations to locate the U-boats and redirect the convoys. Dönitz was flooding the Atlantic with U-boats, havig obtained Hitler's support for a mssive U-boat building program. (After Barbarossa failed before Moscow and declaring war on America, it was obvious that unless the sea lanes could be cut, Germany would be caught in the same two front war that had spelled disaater in World War I.) And with the increasing number of U-boats, it became increasingly difficilt to find safe routes for redirectiong the convoys. It is at this time that several factors came together to tip the ballance to the Allies. The Bletchey Prk code breakers finally began to break into Shark. This frustrated Dönitz because despite the number of U-boats deployed (40 on patrol in the vital North Atlantic convoy lanes), theu were not finding convoys and sinking ships. And he did not know why. And at the same time the Germans began having difficulty with British Naval Cipher 3. This helped with redirecting the convoys, but given the number of U-boats redirection was no longer such an effective method as it once was. Now the Royal Navy and the U.S. Navy would have to shoot it out with the U-boats and fight the convoys through. And here breaking into Shark was part of several Allied effortsthat came together at the same time. This included a range of technical advamnces, increased escots (from American and Canadian shipyards as well as the soon to b relaesed shiops from victory in North Africa) and the all imortant extension of air cover to include the mid-Atlantic air gap. The battle during January-February swung back and forth with the Germans suceeded in savaging several convoys. Often decrypts saved or failed to save convoys by only a matter of minutes.

Continued Sinkings (Early 1943)

German U-boats in early 1943 continued sinking substantial numbers of merchant vessels, although not as many a Dönitz had anticipated with his expanded U-boat fkleet. The British food supply in early 1943 was down to a few months. The U-boats sank about 100 merchant vessels in 1943, mostly in the first half of the year. That was a rate that could not be replaced even by the Liberty Ships coming out of the new shipyrds. U-boat sinkings were also increasing. A major engagement was fought im March involving 80 merchants, 20 escort vessels, 44 U-bots and numerous aircraft. The U-boats achieved numerous kills in March. Royal Naval reports indicate that in March the U-boats came the closest to cutting Britain's Atlantic life lines. The engagements in the North Atlantic were, hioever, no longer one-sided. American shipyards were mot jut building Liberty Ships, they were also steadily expnding production of escort ships. In particular, three new escort carriers were delivered (April). The Allied sank 15 U-boats in April 1943. More than in the past, but still not enough to deter the Germans. After the German defeats in the East amd North Africa, the North Atantic comtinued to be the onle paves where successes were still being achieved.

Black May (May 1943)

The war at sea turned a few months later--May 1943. German intellience learned of a major 43-ship convoy from Britain to America, ONS-5, with only six escorts. It departed (April 22). At first it had air cover. Dönitz ordered a massive 40-U-boat force of two Wolf Pack to form in th mid-Atlantic air gap. It was the largest U-boat force ever committed. They were to attack in force to demonstate the power of his expanding fleet. Dönitz radioed, "Fight with everything you got. Strike the eneny dead." It would be a 4-day knock-down drag-out fight. Horton informed the convoy that they were surrounded by U-boats, but they were on their owm in the mid-Atlantic air gap (May 4). The Wolf Pack sank seven merchantmen on the first day. The next day the U-boats pressed the attack. Allied escorts with little air cover engaged the Wolf Packs. ONS-5 would lose 12 merchant ships. But in the single engagement 6 U-boats were sunk, 5 wrecked, and 12 damaged. In just one battle they did far more damage to the U-boat fleet than in any other month of the war. That totaled nearly a third of the U-boats on patrol in the convoy lanes. It was a stunning reversal and notably it was achieved by only 6 escorts with no air support. And further German losses cointinued during the rest of the month. Dönitz formed another large Wolf Pack to attack a convoy. This time the resukt was even more disterous for the Gemans. They lost five U-boats and did not sink a single merchantman. During May the building Allied naval strength in the Atlantic and widening technical superiority succeeded in sinking 41 U-boats and damaging 37 others. Among the lost crews were Dönitz's younger son Peter on U-954. (His older son Klaus would be killed later in the War.) and even worse for Dönitz, the Allies were in the process of closing the mid-Atlantic air gap as well as deoloying improved radars and ASW weaponry.

Breaking off the Campaign

At sea the U-boats by mis-1943 were no longer the hunters, but the hunted. Increasingly after May there was less and less a chance of a U-boat returning from a cruise. Dönitz had to break off the campaign in the North Atlantic. The Germans by the end of 1943 had built 442 U-boats, but had lost 245 of them. After mid-1943 the Allies were able to deliver convoys virtually unmollested across the Atlantic. It meant the strategic bombing campign could be intendified and the build-up for the cross-Channel invasion could continue with little German interference. Even so the Dönitz persisted. His assessment was the battle in the Atlantic was lost. He believed, however, that even limited operations could tie down vast Allies resources. We are not entirely sure what he told Hitler. The Battle of the Atlanhtic was the last German campaign to turn in the Allies favor. The war in the East and North Africa had shifted at the end of 1942. The Around the Clock bombing of Germany had begun (January 1943). Now Hitler and Dönitz as in the other areas cold only pin their hopes on technological breakthroughs and the defeat of the inevitable cross-channel invasion.

Refined Allied ASW Operations

The Royal Navy thought that they had solved the submarine problem in World War I. Admiral Dönitz and a small number of U-boats quickly disabused the Admiralty of this poorly founded assumption. The Americans despite working with the British were also unprepared to deal with the U-boats after Hitler declared war. Britain's North Atlantic life lines were so vital, that the campaign against the U-boats became a high priority for the Allies. Britain and America unleased their scientists and industry on the U-boat problem. U-boat pens and shipyards became a priority target in the strategic bombing campaign. Cracking the Marine Enigma became a high priority. Escort efforts were expanded by building more ships and imroving the SAW capabilities. The Canadian Navy was expandded to provide much of the North Atlantic escort duties. The Allies by 1943 not only had the cpbility of ecorting the convoys, but went ovr to th offensive organizing Hunter Killer Groups. And they began targetting the Bay of Bicay where the U-boats based in French ports began their Atlantic patrols. And the Allies steadily expanded their air coverage of the Atlantic. In addition the air units developed much more leathal methods and armament to attack the U-boats. The Allies begam working on these ASW avtiions soon after the War began. They eventually came togther in mid-1943 to produce a very effective ASW capability that suceeded in defeating the Gernman U-boats just at the time that Dönitz haf the number of U-bosats that he thought could win the War. Substntial numbers of U-boats as a result were destroyed in 1943-44. After D-Day it became if no suisidal, extremly dangerous to go out on Atlantic patrols.


Strategic Bombing

Even damaging U-boats were important because by 1943 the expanding Allied strategic bombing campaign had brought German ports and shipyards under increasingly intensive attack and the U-boat facilities were a priority target. And their coastal ocation meant that they were smong the most vulneravble targets in Germany. They were an easier target than the industrial cities located deeper in the Reich. German ports all located in the north were much more vulnerable to Allied air attack than the heavily protected cities located in the interior. This made making repairs of serious damage increasingly difficult as the air war progressed. Even minor damage at depths could result in the loss of a boat. So repairs often required major work. The same was true of building new boats. The German response was to build new U-boats in sectioins at secure interior locations and just make the final assembky in the yards. This, however, created problems as the sections commonly fdid not fit together as prefectly as the boats built in the yards. This resulted in major delays in the constructuin of the Tyoe-XXI Electroboats. The increasing pressure on the German rail system from the strategiuc bombing campaign also caused problems.


Convoys and escorts

Hunter Killer Groups

Througout the first 3 years of the Battle of the Atlantic the harf-pressed Royal Navy and then the American Navy only had the resources to escort the convoys and often inadequately. By 1943 the escort situation vwas improving. American shipyards were turning out large numbers of escorts and the Canadians managed to produce large numbers of small escorts. This meant that by 1943 the resources were availabe to put together hunter killer groups. The American groups included escort carriers. The leading British figure in developing hunter-killer tactics was Commander Frederic 'Johnnie' Walker who when the War broke out about to be retired. He soon detinguished himself beginning with the Dunkirk Evacuation and then in convoy escort duties. He then came into his own when he was given command of the HMS Starling, a brand new Black Swan-class sloop and a hunter killer group. He was noted for playing the ditty 'A Hunting We Will Go' over the ship's Tannoy. The U-boats which for nearky 4-years and through lengthy 'Happy Times had been te huters, were now the hynted. Walker racked up more U-boat kills than any other Allied commander and got the pomotion to Captaim he never though he would have. And finally he commanded the Allied naval blocking force that prevented Dönitz's U-boats from getting to the D-Day sea lanes--Operation Cork.

Bay of Biscay Campaign

As Döneitz pulled bck from the convoy lance, the Allies began acampaihn in the Bay of Biscay. This was French coastal waters where the French ports serving as U-boat bases were located. In effect the Allies were going to go after the U-boats in their lair. This was an area where their could be Luftwaffe support. The Strategic Bombing Campaign, however, was forcing the Luftwaffe to withdraw its forces in France back to the Reich to defend the country's industrial cities. This included Operation Stonewall to end blockade running.

Air Cover

The situation only got worse for the Germans. In the first 3 years of the War, Allied aircraft managed to sink very few U-boats. U-boat commanders learned that had little to fear from allied aircraft. British aorcrad=ft sank only 2 U-boats (1939-41). Aircraft drove the U-boats to dive and kept them underwater, thus impairing their operational efficency. Actually sinking them, however, was a different matter. There were a lot of climed sinkings, but very fre actual kills. This began go change in late-1942 as improved radars and ASW weaponry began to come togther to turm airctaft into fearsome U-boat killers. Some 31 boats were sunk by American and British aircraft (1942). The Americans introduce a new long-range B-24, aap able of reaching the Mid-Atlantic Gap. These long-range bombers brought more fire power to the battle than the Catalinas that had been used. And escortscarriers completed the ocean coverage. Some of the changes were simple. One was to change the color of the aircraft to matching the color of the Atantic. Light (Leigh Light) were added to make the planes even more diffucylt to spot. British scientists found that equiopping the planes with a large number of small depth charhes set to dentonte near the surface increased the chnges of an air kill. Improved radars, cracking the sgark ebign=ma code, and expanded dirction finding meant that it becme very dangerous for U-bots to enter the North Atlantic as they had to spend so much time on the surface.

German Reduced Operations (1944)

Dönitz did not end U-boat operations, but sharply reduced them. Even if they could not sever Britain;s lifelines, they did tie up considerable Allied forces. This was done, however, at great cost the to U-boat crews. The expanding Allied ASW effort made in increasingly dangerous for U-biats to operate in the North Atlantic. After the defeats of 1943, Dönitz was no longer able to operate wolf packs in the Atlantic. He never entirely withdrew his U-boats. Sespite the increasing danger of Atlantic operations, even a small number of U-boats forced the Allies to maintain a substntial ASW effort, tieing up mean a resources. Bombers patroling the Atlantic wee mot bombing Germn cities.


The German battlship Bismarck was perhaps the mlost famous ship of World War II. There were two Bimarck class battleships. Bismarck's sistership was Tirpitz, the German admiral who was the father of the country's highseas fleet. Fortunately for the British, it was not ready to sortee out into the Atalantic with Bismarck. Both were massive 44,755-ton class battleships. It was laid down at Wilhelmshaven (November 1936) and Launched (April 1939). She was finally commissioned (February 1941). Tirpitz operated in the Baltic for sea trials and training for several months. She was given combat missions associated with Operation Barbarossa, the invasion of the Soviet Union (June 1941). Tirpitz was ordered into Norwegian waters (January 1942). She was first based at Trondheim in northern Norway. Subsequentyly she appeared in various fjords further north. The Germans used her as potential threat to the Arctic convoys supplying the Soviet Union. Presumably because of the fate of Bismarck, OKM never commited her to a fleet action. She was involved in an actiin at Spitzbergen, firing on shore targets (September 1943). Given her fore power, the Royal Navy was committed to destroying Tirpitz. As the tide turned in the North Atlantic, more assetts were becoming available to the British. The first major was a Brotish attack with five midget submarines referred to as X-Craft (late-September 1943). They caused serious shock damage. While still under repait, Soviet bombers hit Tirpitz, but achieved only one near miss (February 1944). Next the Royal Navy mounted a massive fleet action against Tirpitz which had been largely repaired (early-April 1944). Six Royal navy carriers launched attacks, achieving several hit but with relatively small bombs. This meant additional repairs were needed and Tirpitz was out of acrion for a few more months. Next long-range British Lancasters went after (July-August 1944). Somoke screens affected bombing accrracy. Finally Bombr Command caught Tirpitz in the open on a clear day. Tall boys boms hit the ship in the bow causing massive damage (mid-September 1944). The Germans moved her to Troms� (October 1944). The British continued to pound her. Lancs struck again and delivered tall boys which both hit and futher damage was cauded byn near-misses (November 12, 1944). As a result of the massive damage, Tirpitz listed heavily and after a magazine exploded, rolled over. Some 1,000 crew members were lost.

U-boats: Final Year (June 1944-May 1945)

The Battle of the Atlantic was finally decided with climatic convoy battles (May 1943). Allied naval escorts and aircraft with improving technology managed to destroy substantial numbers of U-boats during Wolf Pack attacks on convoys. The turning pount was ONS-5. The convoy manages to fight off the U-boat wolf packs with only a small escort force. Other losses occured during May and with expaned aerial covrage, the U-boat losses were unsustainable. D�nitz did not withdraw completely from the Atlantic. He calculted that a minor continued commitment would force the Allies to maintain major forces in the Atlantic. The Allies greatly expanded their air coverage, both long range aircraft and escort carriers. Both the Americns and British formed formidable hunter-killer groups. As Allied ASW capabilities continued to improve, many of the U-boats that did go out never returned. The hunter became the hunted. And Allied air patrols were no longer limited to visual spotting, but radar capable of picking up even a persisope. The U-boat service became the most dangerous service of the War. The last important opportunity that Dönitz's U-boats had to play in the War was the Allied cross-Channel invasion D-Day. The plan was once the invasion began that the U-boats would mass in the Channel and sink Allied shipping. The Landwirte Group of 36 U-boats was given the task of atttacking invasin shipping. Unlike the land forces, they did not need to know which landing beach and when. The U-boat effort, hwever, was a total failure. The Allied plugged both ends of the Chnnel with mines, destroyers abd escorts wth ASW capability, and aerial patrols--Operation Cork. As a result, very few U-boats broke into the Channel after D-Day. [Schofield] Few of the U-boats succeeded. There wwre a few successful attacks: HMS Blackwood, Columbine, SS Maid of Orleans, and a few smll ships. Several more ships were damaged. Given the Dimensions of the Allied naval force, the whole effort was ineffectual. The Germans worked on technical innovations of their own. They developed a stealth U-boat with ruberized coverings of the hull. The U-480 was fitted with this covring. It was effective, but developed too late to have any real impact. U-480 was sunk by a minefieldin the Channel laid as a result of Enigma decrypts (February 1945). By 1945, Allied ASW capabilities were so advanced that it was nearly a death sentence for a German crew to take a stabndard U-boat out on patrol in a standard U-boat. The Germans developed the Type-XXI Elektroboot. It had nmany advanhced features, but had a range of problems. And the Allied strategic bombing campaign delayed and complicated construction. Thus the few boats built never went out on a combat patrol. The primary use of the U-boats after D-day was to ship secret technology and enriched uranium to the Japanese. Rumors after the War circulated that U-boats were being used to help top NAZIs escape. There is no evidence of this. Until commiting suiside, Hitler was having people shot for admitting defeat. And there is no evidence that D�nitz facilitated the escape of any NAZI war criminal. The last U-boat sunk by the Allies was the U-3523, a Tyoe XXI. It was sunk by a British crewed B-24 Librator in Danish waters -- the Skagerrak Straits (May 6, 1945).

Decisive Factors

The Allied victory in the North Atlantic was due to a range of factors. Key to the Allied victory was air cover, inteligence, and radar/sonar. [White] More than any other factor, it was the expanding Allied air cover which doomed the NAZI U-boat campaign. The United States built more than 100 aircraft carriers during World War II. Most of the big Essex-class fast carriers were deployed in the Pacific against the Japanese. Allied long-range planes, (Catalinas and B-24s) provided air cover over much of the North Atlantic. Large number of small escort (jeep) carriers filled in the gaps. The Allies also organized submarine killer groups organized around the essort carries. One of these groups organized around the Guadacanal suceeded in capturing the U-505. This was in addition to Ultra decripts and radio directional plotting which provided details on where the U-boats were. The Germans introduced snorkles which would allow them to run their diesel engines underwater, but the snorles could not be used in rough weather and the Allies soon had RADAR dectors that could pick up even the small snorkles. As a result, the U-boats in danger when ever they surfaced--even at night or in deep fog. And German U-boats had to surface for several hours each day to charge their batteries and take in air. The result was that the changes of U-boats returning from a cruie brecame small by the end of the War. Increasigly German U-boats were being lost on their first patrol.

Technological Failure

The U-boat defeat was a failure of German technology. As in other areas, the Germans had an opportunity to win before the American and British technological and industrial capacity was fully mobilized. Unlike the Allied navies, the Kerigsmarine did not receive priority in the allocation of resources. The Allies had a limited ASW capability at the beginning of the War, but grdually developed a very substntial effort. The Germns never matched the allied effort. They made some advances, but were unable to keep up with the improving Allied ASW capability. We are not sure why this was. Certainly they lacked the rsources that the Americans brought to the effort. Wether other factors were involved, we do not know. One seriuious duisadvantage is that the Gernmans were necer entirely sure why they were losing U-boats. When a U-boat was sunk, all the Germans knew was that it was no longer reporting. Thus the German scientistrs were often operating in the dark. It thus took them some time to adjust to Allied advances. And they also faced the overwealming superiority of the Americabs to replace lost merchnt ships with Liberty ships as well as the huge output of esort vessels, including escort carrietrs.


Budiansky, Stephen. Blackett's War (Knopf: 2013), 306p.

Freidel, Frank. Franklin D. Roosevelt: Rendezuous with Destiny (Little Brown: Boston, 1990), 710p.

Lash, Joseph P. Roosevelt and Churchill, 1939-1941 (1976).

White, David Fairbank. Bitter Ocean: The Battle of the Atlantic, 1939-45 (Simon & Schuster, 2006), 350p.


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Created: May 5, 2003
Last updated: 2:44 PM 6/29/2018