In September 1942, "Mary Luckenbach" was part of Convoy PQ 18, a convoy of 40 merchant ships under heavy escort transiting the Barents Sea en route Murmansk in the Soviet Union. On 14 September 1942 (some sources list 13 September), the convoy was west of North Cape, Norway, when "Mary Luckenbach" was attacked by several German Junkers 88 torpedo bomber aircraft and was hit by an aerial torpedo. The impact of the torpedo detonated the ship's cargo of 1,000 tons of TNT, vaporizing her along with her entire crew of 41 and the 24 personnel of the United States Navy Armed Guard assigned to her. Her sinking is described in the memoir of Robert Hughes, a gunnery officer on HMS "Scylla". The last known location of the ship was at .