On 18 December 1941, five German U-boats set out for the east coast of North America. The attack on Pearl Harbor had occurred a week and a half earlier, with the United States declaring war on Japan and then on Germany in the days following. Karl Dönitz, head of German U-boat operations, saw the declaration of war as his chance to finally attack American merchant shipping, which had previously been off limits due to Hitler’s worries that it would bring the U.S. into the war. Dönitz wanted to attack American shipping at its source, before anyone would be expecting it and while the Americans were distracted by the aftermath of Pearl Harbor. To ensure the secrecy of the mission, even the U-boat captains didn’t know their destination until they were already at sea. Upon reaching North America, two of the U-boats went to Canada, while three continued on to the U.S. It was the beginning of what was known by the Germans as Operation Paukenschlag (Drumbeat).
The Germans found the waters off the U.S. East Coast to be a U-boat’s paradise. Coastal cities were still brightly lit at night (instead of instituting blackouts to prevent ships being silhouetted against the city lights), and ships were still operating under peacetime conditions: traveling one by one—rather than in convoys—with their navigation lights on. After U-boats sunk two ships off the coast Nova Scotia, Canada, a U-boat sunk a Panamanian tanker off the coast of Long Island on 14 January 1942—the first ship to be sunk in this operation in American waters. In the first two weeks of Operation Drumbeat, the five U-boats sank 23 ships. Since the mission was so successful, Dönitz sent more U-boats, which continued with their easy pickings for the next seven or eight months, sinking 609 ships while only losing 22 U-boats.
Despite the heavy losses to merchant shipping, American naval leaders were generally apathetic toward the problem. Admiral Ernest King, commander-in-chief of the U.S. fleet, largely ignored British warnings to institute the convoy system, even though it was well known by this point that convoys dramatically reduced the number of ship sinkings. King, focused on the war in the Pacific, argued that he didn’t have enough destroyers to provide East Coast convoys with protection. After much protesting from others, King finally decided to institute limited trial convoys in April and, when this drastically cut the number of losses, shifted over to full convoys with aircraft coverage by mid-May. This effectively ended the free reign the U-boats had in American waters, but by then around 5,000 people had already died in U-boat attacks.