Figure 1.--

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. As Allied ASW capabilities continued to improve, many of the U-boas that did go out never returned.

Technology

Britain and America unleased their scientists and industry on the U-boat problem. The Germans began World War II with a very small U-boat force. The U-boats proved more effective than the British and the German Admiralty had expected. It was unable, however, to significantly impair the British war effort because of its small size. The major impact was to alert the British to the potential danger and give the British time to prepare for the massive U-boat campaign which the Kreigsmarine would eventually mount. The Admiralty did not have a lot of time, but they made good use of the time they had, in part because Churchill at the Admiralty and later as prime-minister strongly supported ASW efforts. Mineswweping was the most immediate success. Laying mines was given condiderable priority by the Kreigsmarine, despite Dönitz's opposition. Many of the British ships sunk in the opening months of the war struck mines. The new German magnetic mines were especially effective, but British scientists successfuly developed countermeasures. The Double-L system was employed (early-1940). Degausing procedures were implemented for ships. Radar was another ASW effort and as in the air war would prove to be a major success. The British develooped the cavity magnetron which made it possible to minurize radar sets so they could be put on planes. This would ultimately allow ships and planes to detect a U-boat with only the periscope above water. The British would, however, need the Americans to produce the sets in numbers. A BBC science writr claims that "It is impossible to exagerate the importance of Randall and Boot's work. It lifted radar from an electronic stone age to the present day." [Johnson] It took some time , but by 1943, American industry was turning out vompct radar sets that could be put on small escors and eventually aircraft. 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.In addition new weapons such as hedgehogs were developed.

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.

Ultra

Codebreaking was another important effort. The British effort at Bletchly Park to crack the German Enigma machine made considerable progress. It at first made little progress with the Naval Enigma, primarily because of the strict security procedures Dönitz insisted be followed. Bletchly Psrk brok into Enigma, but then Dönitz insisted on a fourth rotor. This problem was not solved until 1943. Cracking th marine Enigma and the the British Y Service evntually meant ghst U-bosts could be tracked down snywhere in the Atlantic. Dönitz's penvchant for remaining in viotsct with his U-boat commanders was a great assuistant to the Allies.

Convoys and escorts

Convoys were the principal World war I precaution. The British developed a convoy system, although authors disagree about the advisability of doing this before the Germans had a more substantial U-boat force deployed. Adm. King first opposed convoys when Anerica ebterested the War. His primary conbcern was a lack of escorts. And this was a major problem, especially before America enterested the War. With America in the War the Arsenal of Democracy began turning out eascorts,n other warships, and merchantmen (Liberty Ships) in numbers the Germans never anticiopated. Escorts were small ships, as a result the Canadians began building them in large numbers-something else the Germsns never anticipated. More than numbers, however, were involved. A U-boat could sink an escort. Upgraded weaponry and radar even the odds. By mid-1943, the escorts were safelly bringing convoys over to Britain without losses.

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. Of course after D- Day the Germans began losing their all important Atlantic ports and access to the Ny of Biscay.

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. Air cover was limited to coastal areas and attacks on U-boats were disappoijting. 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 Allies greatly expanded their air coverage, both long range aircraft and escort carriers. 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 shark enigma code, and expanded dirction finding meant that it becme very dangerous for U-boats to enter the North Atlantic as they had to spend so much time on the surface.

Created: 8:02 PM 6/29/2018
Last updated: 8:02 PM 6/29/2018