At 07.52 hours on 8 Apr 1942, the unescorted and unarmed Oklahoma (Master Theron P. Davenport) was sunk in very shallow waters by U-123 (Hardegen) about 10 miles off St. Simon´s Island, Georgia.
The Oklahoma was later refloated and towed to Chester, Pennsylvania where she was rebuilt and returned to service.

At 05.45 hours on 28 March 1945 the unescorted Oklahoma (Master Alfred Mathesen) was hit by one torpedo from U-532 while steaming on a nonevasive course at 14.5 knots. The torpedo struck on the starboard side between the #6 and #7 tanks aft of the pump room, igniting the cargo and the tanker exploded. The wind and the speed of the ship kept the flames aft, allowing some of the eight officers, 38 crewmen and 26 armed guards (the ship was armed with one 5in, one 3in and eight 20mm guns) to abandon ship in two of the forward boats in the rough seas and force four winds. But one of the boats caught fire and the four occupants had to jump into the water, while the other boat rowed around the wreck picking them up and looking for more survivors. Flames surrounded the ship for a distance of 500 feet and the flaming cargo blazed on the water a mile astern.

The lifeboat containing four officers, six crewmen and twelve armed guards was not seen by a PBM aircraft and an US Navy blimp on 11 April, but three days later another aircraft directed the American steam tanker Delaware to the survivors in 11°45N/66°06W. They were landed at San Nicholas, Aruba on 15 April. The Oklahoma was last seen ablaze from stem to stern and eventually sank.