At 04.53 hours on 1 Dec 1939 the unescorted and neutral Mercator (Master Gunnar Nilsson-Ollandt) was hit near the foremast by one G7a torpedo from U-21 about 12 miles southeast of Buchan Ness and sank after six minutes. One crew member was lost. The U-boat had spotted the ship with lights set only 13 minutes earlier and attacked because no national markings were visible. The RNLI lifeboat Julia Park Barry of Glasgow and the motor fishing vessel Bread Winner put out from Peterhead to rescue 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.