At 18.54 hours on 21 April 1942 the unescorted Pipestone County (Master Richard E. Hocken) was hit by one torpedo from U-576 about 475 miles east of Cape Henry, Virginia. The torpedo struck in the #1 hold, which was flooded but the engine room was still intact and the ship was still moving. At 19.14 hours, a coup de grâce was fired that struck in the #2 hold and caused the ship to sink after six minutes. The nine officers, 28 crewmen and nine armed guards (the ship was armed with one 4in, four .50cal and four .30cal guns) abandoned ship in four lifeboats and one raft. They were questioned by the U-boat, which also gave provisions to the men in one of the boats. The survivors on the raft were transferred into the boats, which were later separated because of rain and moderate seas.

The 23 men in two of the boats were picked up by the Norwegian steam merchant Tropic Star on 24 April and landed at Boston the next day. The eleven crew members and two armed guards in a third boat were picked up by USCGC Calypso (WPC 104) on 7 May and taken to Norfolk, Virginia. The ten men in the last boat were rescued on 8 May by the American fishing vessel Irene and May and landed at Cape May, after they were spotted by an US Coast Guard aircraft from Elizabeth City, North Carolina.