Battle of the Atlantic: Air Component


Figure 1.--Here General De Gaulle is seen shaking hands with children in L'Orient, 2 months after VE-Day (July 1945). L'Orient is a port in Brittany which juts out into the Atlantic. It was one of the most important Germn U-boat bases and as a result heavily bombed. The British at a critical pont of the Battle of the Atlantic heavily bombed the port in an effort to prevent the U-boats from operating there (January-February 1943). They dropped 500 high-explosive bombs and more than 60,000 incendiary bombs. The U-boats pens were hardened, bit the city was almost completely destroyed.

The Battle of the Atlantic was of course a naval campaign, but there was an important air compnent to it. The Luftwaffe contributed small forces to the Battle of the Atlantic. Tghe Allies devoted much larger air forces. 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 American personnel in Brazil heped close the Atlantic 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 by attacking convoys and ports. Here they had some success at attacking ports as part of the Blitz, but convoy attacks were limited by the small number of long-range bombers and British counter-measures like ship launched fighters. And the Luftwaffe was shifted east as part of the run up to Barbarossa (April 1941). Luftflotte 5 was more successful in attacks on the Arctic convoys. Germany did not have the industrial potential to build long-range bombers to attack the convoys and British ports in force. In contrast the Allies, especially the United States, did have the industrial capacity 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 (especially aircraft radar sets), sonar, and ASW weapons (including air dropped weapons) as well as code breaking forced 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. And Allied air patrols as radar and ASW weapons improved were able to attack the U-boats leaving and returning to these bases. The French bases despite the heavy bombardment continued to function until the D-Day landings and Allied breakout forced the Germans to withdraw (July 1944).

Norway

The Luftwaffe had its first experience in supporting the war at sea during the Norwegian Campaign (April-May 1940). Bases in Norway would subsequently enable the Luftwaffe to attaack the ectic convoys to the Soviet Union.

Allied Coastal Patrols

The British and susequently the Americans had coastal patrols to cover convoys. RAF Coastal Command was responsible for these operations. Air cover from islands such as Bermuda and Iceland covered some of the ocean areas between the two coasts. The Anglo-American Destroyers for Bases deal gave the U.S. Navy additional facilities for ocean patrol. Allies like Brazil were also important. The Brazilians and American personnel in Brazil heped close the Atlantic 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.

British Fleet Air Arm/Air Branch

The British formed the Fleet Air Arm after World War I (1924). The Government was unsure about how to organizational place the Fleet Air Arm. Both the Royal Air Force and the Royal Navy wanted it. During the Inter-War era the Royal Air Force got it. Just before the War, the Fleet Air Arm was turned over to the Royal Navy (May 1939). This was the Inskip Award. Inskip was the Minister for Co-ordination of Defence who headed Britain's re-armament program. The Fleet Air Arm was renamed the Air Branch of the Royal Navy. This control by the RAF may explain why the Royal Navy entered the War with obsolete bi-plane aircraft. The RAF almost began the War with biplanes itself. When the war started the Admiralty was still a Big Gun club and battleships were the backbone of the fleet and still considered the capital ships. Because of this and the administration by the RAF with strict budgetary limitations, the Fleet Air Branch did not have a single modern carrier capable aircraft. At the onset of the Second World War, the Fleet Air Arm consisted of 20 squadrons with only 232 obsolete biplanes. Even so, the Fairy Swordfish, a slow biplane torpedo bomber did play a role in the War. It was used for an attack on an Itlian naval base at Taranto (1940). Only 21 aircraft were able to get to the target but they were able to heavily damage three of the six Italian battleship in the harbor and a few other smaller ships. This attack on such a shallow harbour had the unfortunate side effect of convincing the Japanese that an air attack on the shallow waters of Pearl Harbor was doable. Swordfish also played a keyrole in the Bismarck operation (March 1941). The Royal Navy's primary assignment in World War II was the Battle of the Atlantic to keep the sealanes open with North America. Churchill wrote after the War that this was the one campign he was most concerned with. The Admiralty worked out early on that air cover would be key to winning the extended battle. World War II submarines could not operate with enemny aircraft overhead. The British began by orgnizing hunter-killer groups--fleet carriers protected by destroyer esports. These anti-sunmarine patrols, however, exposed the valuable carriers. This was especially the case early in the War when ASW operations were still primitive. SONAR (ASDIC) was still relatively poorly developed and dangerously did not have as wide a range as the U-boats torpedoes. The result was almost as soon as the patrols begn, the loss of HMS Courageous (September 17, 1939). The loss of one of the Royal Navy's most powerful ships was a traumatic reevation at the Admiralty. The answer was escort carriers, relatively small, disposable ships converted to serve as carriers. This provided air cover without putting indespensible capital ships at risk. It also increased the number of anti-submarine patrols and the number of convoys which could be covered. HMS Audacity was converted from the captured German merchant ship MV Hannover (July 1941). She was sunk by a U-boat but in the action several U-boats were sunk or damaged, proving the escort carrier concept. Primeminister Churchill urged the concept on President Roosevelt and it was adopted by the U.S. Navy. In the crisis of the Battle of Britain (July-September 1940), Fleet Aur Branch pilots were temorarily transferred to RAF Fighter Command which was desperately short of trained pilots. The Royal Navy's Air Branch strength reached 59 carriers (mostly escort carriers), 3,700 aircraft, 72,000 officers and men, and 56 Naval air stations by the end of the War, much of it deployed to the Pacific after VE Dau (May 1945). The British never did devlop modern crrier aircraft. They modified some Hurricans and Spitfires, but primarily used merican carrier aircraft. They used the American Wildcat, Hellcat and Corsair as both fighters and fighter bombers.

Kriegsmarine Bases in France

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 provided fighter cover for U-boats moving out into Atlantic patrols and then returning back to base. The Lufwaffe also offered cover to returning blockade runners until the Royal Navy eliminated these vessels. 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. And Allied air patrols as radar and ASW weapons improved were able to attack the U-boats leaving and returning to these bases. The French bases despite the heavy bombardment continued to function until the D-Day landings and Allied breakout forced the Germans to withdraw (July 1944).

Luftwaffe Support

The Luftwaffe attempted to support the U-boats by attacking convoys and ports. This was possible only after the defeat and occupation of France provided bases near the Atlantic coast. (The etire Atantic coast was in the occupied zone.) The Luftwaffe had some long-range reconnaissance planes. These included first the Focke-Wulf 200 and later Junkers 290 maritime patrol planes. The Focke Wulf planes were initially successful. The numbers were, however, limited, The planes could both attack as well as aleet U-boats of convoy locations. The were responsible for 365,000 tons of shipping (early 1941), but the number of these long range recon planes were limited. The first British counter-measure was to launch specially equipped Huricanses from convoy ships. This significantly reduced the effectiveness of the German reconnaissance flights. The development of escort carriers and increased efforts by RAF Coastal Command were a more permanent sollution. The Luftwaffe introduced the He 177 bombers with guided missiles which scored some successes. The Luftwaffe also had targetted British ports as part of the Blitz. This ended when the Luftwaffe was shifted east as part of the run up to Barbarossa (May 1941). Luftflotte 5 was more successful in attacks on the Arctic convoys.

Mid-ocean Gap

As the Battle for the Atlantic developed, the Allies relied heavily on air power. During World War I, the German U-boat effort tended to be close to coasts because of the limited range of the U-boats. This changed dramtically in World War II. Growing Allied air power, especially after America entered the War with its phenomenal productive capacity. Air bases ringed the North Atlantic gradually forced the U-boasts deeper into the Atantic. The Irish Free States did not permit Allied bases, but air bases in Scoitland, Ulster, Iceland, Greenland, Labrador, the Canadian Maritimes, the United States, and Bermuda provided air cover for the convoys for most of their voyage. And with air cover overhead the U-boats could not surface and attack. Submerged they were too slow to keep up with and attack the convoys. And it was not just the bases, but the Allies commited more and more aircraft with increasing capability and range. The Allies flyers through 1942, however, were not good at actually sinking U-boats, but there mere presence made it difficult for the U-boats to even operate. At the beginning of 1943 there still remained a substantial mid-ocean gap with no air cover for the convoys. It would be here that the decisive convoy battles of the Battle of the Atlantic were fought out. And they were fought out by a small number of escorts with improved weaponry and equioment against huge assemblages of U-boat wolf packs. The turning point was ONS-5 (May 1943). This occured before the mid-ocean gap was closed. Adm. Dönitz had to withdraw his U-boats from the convoy routes even before the mid-ocean gap was closed. The aircraft available even in early-1943 could not close the gap. This was finally closed with long range B-24 Liberators became available in large numbers at the same time the escorts of ONS-5 fought odd the lsrgest U-boat assemby of the war. ss. The B-24s not only had a longer range tht the Catalinas, but could carry a substantial load of anti-submarine weapons. There were 50 liberators flying from bases in Ulster, Iceland, and Labrador (May 1943). This meant the end of the U-boat threat.

Industrial Capacity

Germany was an imprtant world industrial power, but it did not have the resources and industrial capcity to wage a protacted world war. Waging war with Britain and France was one thing. Wageing war with Britain, the Soviet Union, and the United States was quite another. As a result, Germany was forced to fight the War without an important surface fleet, basically World war I U-boats, and without long-range bombers to attack the convoys and British ports in force. In contrast the Allies, especially the United States, did have the industrial capacity to build the aircraft needed for not only the Battle of the Atlantic, but for a massive strategic bombing campaign. As well as to build more shipping than the U-boats could begin to sink. American shipyards by mid-May had replace all the merchant men sunk and then began to build a hughely expanded merchant marine to support the war effort.

Allied Strategic Bombing Campaign

The Allies began the strategic bombing campaign by droping leaflets on Germany. With the fall of France, German targets were beyond the range of any mjor campaign, although Bomber Command did conduct small night raids. Only with the arrival of the Lancaster, did Bomber Command have the instrument for launching a significant campaign (1942). The United States joined the British with an around-the-clock bombing campaign. And one of the highest priority targets was the shipyards buiding U-boats. These were some of the easiest targets to reach and find. They were located in the north along the coast.

Air Tactics and Technology

Air coverage from the beginning was inva;uable in protecting the convoys. It forced the U-boats from the surface where they had to be to operate effectively. This provided important prorection to the convoys. But the air attacks on U-boats proved very disappointing in actually achieving actual kills. German propagands found it amusing the number of times the allies claimed destoying U-boats that were actually untouched. The basic problem was that Allied aircraft could only attack during the day and they could be observed before the planes could get close enough to attack. The U-boats usually had time to submerge and escape. This continued until late-1942. The first major change was very simple. British scientits suggested that the aircrft should be repaited to match the sky meaning that that they were less easily observed. Scientific adviswers also suggested dropping several small bombs rather than one large one. The key developmentin in the Allied air effort was the cavity magnetron feveloped by the Btitish before the War. This allowed the minaturization of radars so they could be installed on aircraft. American companies perfected the British invention and began produciung them in hige quantities. This allowed the U-boats to be dected day and night. And eventually they were so effective that they culd detect the U-boats if only a periscope was above the surface. Amerian and British directional systems could locate general ares by picking up signals. The radars could them hone in on the U-boats. Finally Allied air kills began to mount.

Hunter-Killer Groups

Even with long-range air patrols, the mid-ocean gap while closed in the North Atantics, remained open further south. The Allies could not cover convoys with fleet carriers, it would be a misallocation of resources. there were too many convoys and two few large fleet carrietrs, not to mention putting the carriers in harms way. And the American carriers were critically needed in the Pacific. The innovation of escort/jeep (small) carriers not only helped provide air cover for the convoys, but also the creation of hunter-killer groups to actively hunt down the u-boats. The tipping pont of the Battle-of-the Atlantic was a fight over several convoys attacked by U-boats (June-July 1943). For the first time substantial numbers of U-bosts were sunk in these hard-fought naval battles. And after that the hunter-killer groups took the offensive against the U-boats. Between the long range B-24 Liberator and many other patrol planes and the use of hunter-killer groups of anti-submarine ships built around one or more jeep carriers and as many as eight destroyers. By 1943 Fletcher-class destroyers were becoming invreaingly available for ASW operations. The key to the success of the hunter-killer groups was Ultra. The Atlantic is a big place. Patrolling the whole Atlantic, even the whole North Santic would have ben very costly requiring enormous resources. Thankfully, Dönitz was a control freak. He demanded his U-boats report their location and he gave them instructions back daily or even more frquently. And supply deliveries with Milk Cow subs required coordinaton. Thus the Hunter Killer groups would get daily reports on the coordinates where U-boats might be found. The Hunter Killer groups and long-range air patrols forced the German U-boats away from the major convoy routes and eventually began to find and attack the U-boats even in remote areas. Döntiz was forced to withdraw the U-boats from the North Atalntic conviy routes. And as the Allies perfected their ASW operations, serving on U-boats became one of the most dangerous assignments during World War II.

Ultra

The Allies deployed enormous resources in the North Atlantic first to to escort convoys and then to hunt down and kill the U-bosts. The Atlntic is, however, a big place. Huge resources beyond the ability of even Allied shipyards and aircradft plants would have been needed to even find the U-boats. This last piece of the anti-Ubost effort was provided by British code breakers at Bletchly Park. Dechipering Naval messages proved the most challenging of the attack on the the machines of the three German military services. After surviving the Battle of Britain (September 1940), the Kriegsmarine codes took on greater urgency, primarily but not only because of the U-boat campaign in the North Atlantic. The Kriegsmarina Enigma machines were also cracked, but was very difficult because Dönietz insisted that operators carefully folow security protocols. The effort was given a major assist when the Royal Navy captured the German armed trawler Krebs off Norway (March 1941). The boarding party found the Enigma machines in tact along with associated codes. Admiral Döntiz had growing security concerns and, as a result, a fourth rotar was eventually added to the naval Enigms. This sounds not all that important, but mathamatically in greatly increased the complexity of the transmissions. The introduction of the more complex Enigma cypher put the Allies in the dark at a critical time of the Battle of the Atlantic (early-1942). Alan Turing was joined by Hugh Alexander, a British chess grandmaster and others to attack the naval Enigma messages. Alexander became one of the most important Bletchley code breakers. [Smith] The Royal Navy again managed to obtain an intact Enigma machine and associated material needed to set the machines. It took several months, but Bletchley Park finally broke back into the four rotor naval Enigma messages (late-1942). This set up the final phase of the campaigmn against the U-boats (early-1943). Cracking the Kriegsmarina Enigma machines would play a major role in the defeat of the U-boat campaign in the North Atlantic. British and American code breakers. decrypoting naval Enigma messages provided the Allies accurate information on where the U-boats were. Admiral Dönitz was what may be termed a 'control-freak'. He conducted the Battle of the Atlantic ftom his headquarters. To do this and to forn wolf packs, he needed to know where the U-boats were located. This proved disaterous for the U-bosts once the naval Enigma codes were broken and the Aliied hunter-killer teanms were deployed. Cracking the naval Enigma not allowed the Allies to not only reroute convoys, but allowed the hunter-killerr groups to focus their pstrols on the areas that the code breakers identified. Doomed U-boat commanders would proceed to areas where they not only did not find convoys, but Allied hunter-killer groups with hifgly effective ASW weaponry.

Allied Air Dominance

Allied air dominance in Europe also played a role. The Allies did not achieve air superority oiver the Reich in 1943, bit they did over occupied France, including the Atlantic ports with U-boat bases. Thius allowed the Allies to hammer the bases. The hardened-Uboast pens were virtually invuknerable, but the rail lines carrying supplies to the U-boat pens were not. And the Allies were able to intensify air patrols catching U-bots leaving and trying to reach the hardened pens. Many U-boats were hunted down in their home waters near the occupied south-western French coast.

Allied Technical Advances

Technical advances in radar (especially aircraft radar sets), sonar, and ASW weapons (including air dropped weapons) as well as code breaking forced 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.

Sources

Smith, Michael. Station X: The Code Breakers of Bletchley Park.







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Created: 9:10 AM 8/4/2011
Last updated: 6:53 PM 6/18/2017