At 04.53 hours on 1 Dec, 1939, the unescorted Mercator (Master Gunnar Nilsson-Ollandt) was hit near the foremast by one G7a torpedo from U-21 and sank in six minutes southeast of Buchan Ness. One crew member was lost. She had been spotted 13 minutes earlier with lights set, but without visible national markings. The Peterhead lifeboat Julia Park Barry of Glasgow and the motor fishing vessel Bread Winner put out from Peterhead to rescued the survivors. 19 men in a lifeboat and a raft lashed alongside it with four others were picked up by the fishing vessel three miles east-northeast of Peterhead and brought to the port. The twelve remaining survivors in a second boat rowed towards shore and made landfall at Boddam during the morning.