A Summary Antisubmarine Warfare Operations in World War II

Washington: National Defense Research Committee, 1946. — 193 p.This first phase of U-boat warfare was greatly influenced by the rapidly changing overall military situation. Germany invaded Poland on September 1, 1939, and England and France declared war on Germany on September 3. Some U-boats had left Germany early in August and when the war began there were about six at sea, ready to start an offensive in the Northeast Atlantic in the Western Approaches to England. According to statements of early prisoners of war, the commanding officers of U-boats had been ordered to observe International Law, which forbade U-boats to sink merchant vessels without having first placed the passengers and crew in a place of safety. At the beginning of September, these instructions seem to have been generally obeyed, with the notable exception of the Athenia, which was torpedoed without warning on September 3. However, this situation did not last long and, toward the end of September, even neutral ships were being torpedoed without warning. Anticipating unrestricted U-boat warfare, the British had prepared plans before the war for the immediate establishment of the convoy system and the first trade convoy sailed on September 6. As the British defenses against U-boat attacks were based on the needs of protecting primarily the fleet and secondarily merchant shipping, the limited number of antisubmarine vessels available for convoy escort was
inadequate to provide direct protection to the convoys.