This day in history, January 13, 1942, German U-Boats began operations off the eastern coast of the United States.
The move was called “Operation Paukenschlag,” which in German means “Drum Roll.” Admiral Doenitz faced arguments from his superiors in the German Navy who were not in favor of the operation, and experienced difficulty convincing them that only the larger 740-ton U-Boats were really suitable for such long-range patrols.
When Doenitz gave the order for the attack to begin, there were 11 U-Boats in position and 10 more en route. Together, they sunk more than 150,000 tons during the first month. Intelligence sources had given reasonable warning of the attack, but the U-Boats found virtually peace-time conditions during the operation.
U-boats were able to inflict massive damage with little risk. Ships sailed with lights on at night; lighthouses and bouys were still lit; there was no radio discipline – merchant ships often gave their positions in plain text; there were destroyer patrols (not convoys with escorts). They was regular and predictable, and their crews were naturally inexperienced.