The Atlantic Battle Won, May 1943- May 1945: History of United States Naval Operations in World War II, Volume 10 - U.S. Naval Operations in World War 2

Allied shipping was in a desperate situation in 1942, as the Germans were building U-boats faster than the British and the Americans could sink them. By the summer of 1943, however, the tide had turned, and Germany had lost the strategic initiative in the Atlantic.