At 09.52 hours on 13 Sep 1942, U-408 fired a spread of three torpedoes at convoy PQ-18 about 100 miles southwest of Spitsbergen and observed a hit after 5 minutes 27 seconds on the Stalingrad, accompanied by a column of fire and a boiler explosion. The other two torpedoes missed, but one of them hit the Oliver Ellsworth which had to steer hard left to avoid the torpedoed ship.

The Stalingrad (Master A. Sakharov) was hit amidships on starboard side at the coal bunker and sank in 3 minutes 48 seconds. The crew members and passengers had to abandon ship in the port lifeboats because the others on starboard had been destroyed by the explosion, but one of the boats capsized when reaching the water. 16 crew members and five passengers were lost. The survivors were picked up by British motor minesweepers, accompanying convoy on their transfer to the Soviet Navy.

The master A. Sakharov had left the ship as last man and spent 40 minutes in the freezing water before he was rescued. Nevertheless he served as pilot for convoy and was later awarded the George Cross.