At 20.00 hours on 10 June 1943 the unescorted Esso Gettysburg (Master Peder A. Johnson, lost) was hit by two torpedoes from U-66 about 100 miles southeast of Savannah, Georgia, shortly after she received a U-boat warning, steaming on a zigzag course at 15.5 knots. One torpedo struck the port side between the #6 and #7 tanks, ripped up 25 feet of deck, blew oil 100 feet into the air and disabled the steering gear. Seconds later the second struck on the port side at the engine room, causing an immediate fire as she began to settle by the stern and listed to port. Oil from the two tanks was spread into the water and was ignited by the second explosion. The flames spread 100 feet on both sides, while smoke rose over 1000 feet in the air. The eight officers, 37 men and 27 armed guards (the ship was armed with one 4in, one 3in and eight 20mm guns) attempted to launch some lifeboats, but failed because of the intense flames. Only 15 men (seven armed guards, three officers and five crewmen) survived because they jumped overboard and swam away as fast as they could. The entirely submerged tanker, except for a small part of the bow, was last seen about 03.00 hours on 12 June and eventually sank. The survivors found a badly burned lifeboat after swimming for three hours and extinguished the fire. All were picked up by the American steam passenger ship George Washington the next day after they were sighted by an US Army patrol aircraft and landed in Charleston, South Carolina, the same day.

The armed guards ensign was awarded the Navy Cross.