Defeating the U-boat Menace

By the time the AAF disbanded its Antisubmarine Command in August 1943, the German submarine threat had been reduced to little more than a nuisance. In the Atlantic Ocean between September 1943 and the end of the war, German submarines sank fewer than twenty ships. Although attacks became increasingly rare, the U-boats did tie down large numbers of Allied naval and air forces.

Statistics underscore the menace of the enemy submarine offensive. Germany began 1942 with 91 operational submarines; by 1943, it had reached a peak strength of 212. It built 1,162 submarines, of which 785 were sunk, 156 surrendered at the end of the war, and the rest were scuttled or otherwise destroyed. Despite these astounding losses, the U-boats sank over 2,600 Allied ships, totaling about fifteen million tons of cargo. Between September 1939 and May 1945, German submarines operated over an extremely large area: in the North and South Atlantic Oceans, Caribbean Sea, Gulf of St. Lawrence, Mediterranean Sea, Indian Ocean, Kola Inlet in north Russia; off the east coast of the Unites States; around the Cape of Good Hope; and along the coasts of Australia and Brazil.

The critical battle of the antisubmarine war took place in the North Atlantic between August 1942 and May 1943, when German submarines sought to drive Allied shipping from the transatlantic sea lanes. In August 1942, the submarines were sinking more merchant ships than the Allies could replace, but by May 1943 the U-boats were sinking too few ships to justify their own losses from antisubmarine forces. Thereafter, the German submarines dispersed to scattered patrol areas.

AAF units from the EAME theater participating in the critical Battle of the Atlantic comprised two independent flight operating from Greenland. Elsewhere in the theater, AAF antisubmarine units concentrated on patrolling the key routes at the Bay of Biscay and protecting Allied shipping approaching the Straits of Gibraltar. Despite these important missions, at no time did the number of AAF antisubmarine units active in the EAME theater ever exceed six squadrons.

With their advanced technology and long-range capabilities, AAF forces helped tip the balance of the war against the U-boats in favor of the Allies. Although AAF B-24s destroyed only eight submarines, their extended patrols forced U-boats to submerge and remain ineffective for prolonged periods, allowing essential Allied shipping to escape attack. The key measure of success in antisubmarine warfare is the number of ships not sunk, rather than the number of submarines destroyed. After the war, Dönitz cited the Allies' use of aerial reconnaissance and attack as decisive factors in the defeat of the German submarines.

On  the other hand, strategic bombing proved  less effective against German submarine production or basing than Allied leaders expected in 1942. The bombing attacks on production facilities resulted in some destruction, but until February 1944 the Germans managed to compensate for the damage done. The number of U-boats commissioned reached its peak of seventy-eight per quarter in January 1944 and did not decline below forty-nine per quarter until April 1945. The bombers were also unable to destroy U-boats berthed at their bases until the the defeat of the submarines in the deep ocean and the capture of the protected submarine facilities on the French coast. Force to shelter immobile in unprotected harbors along the Baltic, Mediterranean, and North Seas, the U-boats eventually became easy prey to U.S. strategic bombers, and the threat to Allied shipping and troop movements ended.