On 22 June 1942 the unescorted and unarmed E.J. Sadler (Master Leslie Dean Cushman) was taken under fire by U-159 about 175 miles south of the Windward Passage, as the tanker was 36 hours out of port and proceeding on a nonevasive course at 8.4 knots. At 20.35 hours, U-159 began to shell the ship from a distance of about four miles. The lookouts on the tanker had not seen the U-boat until it opened fire, but now the vessel immediately swung the stern toward it and the radio operator began sending distress signals. Eight of the first ten rounds from the 10.5cm gun were hits and the crew of eight officers and 28 men abandoned ship in four lifeboats. U-159 then fired another 75 rounds and 175 rounds from the 37mm AA gun into the tanker at close range, which set the ship on fire, but the ship remained afloat. After four hours a boarding party was sent aboard and placed scuttling charges, which finally sank the ship.

The next morning a PBY aircraft spotted the survivors and directed USS Biddle (DD 151), which picked them up 20 hours after the attack and brought them to Mayaguez, Puerto Rico.