[O}n the afternoon of July 15, 1942. KS-520—a convoy of 19 merchant ships headed from Hampton, Virginia, to Key West, Florida–steamed about 20 miles off the North Carolina coast with war supplies. U-boats, at times hunting in wolf packs, had been viciously attacking the shipping lanes, especially off Cape Hatteras, sending 154 vessels to the sea floor along the East Coast.
Escorting the convoy were five naval vessels, two Kingfisher floatplanes and a blimp. Lying in wait was the U-576, a 220-foot-long German submarine that had been attacked days earlier, suffering damage to its ballast tank. But Hans-Dieter Heinicke, its commander, couldn’t resist attacking, firing four bow torpedoes. Two struck the Chilore, an American merchant ship. One hit the J.A. Nowinckel, a Panamian tanker, and the fourth tore into the Bluefields, a Nicaraguan merchant ship loaded with kapok (a ceiba tree product), burlap and paper. Within minutes, the Bluefields went to the bottom.
Just after firing, the U-576 popped to the surface only a few hundred yards from the Unicoi, an armed merchant vessel that fired upon it. The Kingfisher aircraft dropped depth charges and soon after sailors from the convoy saw the U-boat upend, props spinning out of the water, and spiral to the bottom.
Hoyt thinks it could be the only site off the coast where an Allied vessel and a German U-boat sank so close to each other...