Merchant Losses to U-Boats 1 January–31 May 1942

Nazi Germany’s declaration of war against the United States at the end of 1941 began a new era of U-Boat attacks against merchant shipping, which was playing a vital role in supplying the UK with food and other equipment. Admiral Dönitz headed Operation Drumbeat using a handful of long range Type IX submarines which would target merchant shipping in North American waters away from British naval forces. In the face of warnings from the British about the vulnerability of US merchant ships, which were travelling alone without naval protection and making no effort to conceal themselves by masking navigation lights, the German U-Boats enjoyed a period of devastating success. Convoy systems were not properly implemented until the threat of the German U-Boats had already peaked. During this period the US Navy’s small, unprepared east coast forces were ineffective against German U-Boats, not successfully sinking one until 14 April 1942.