Convoy SC-121 was the 121st of the numbered series of World War II Slow Convoys of merchant ships from Sydney, Cape Breton Island to Liverpool. The ships departed New York City 23 February 1943; and were met by the Mid-Ocean Escort Force Group A-3 consisting of the USCG Treasury Class Cutter USCGC Spencer, the Wickes class destroyer USS Greer, the Flower class corvettes HMS Dianthus, HMCS Rosthern, HMCS Trillium and HMCS Dauphin, and the convoy rescue ship Melrose Abbey.