At 07.35 hours on 23 Feb, 1943, U-186 fired a spread of three torpedoes at the convoy ON-166 about 310 miles south of Cape Race and observed one hit after 2 minutes 32 seconds on the ship in station #12, the Hastings, which was erroneously reported as Hassop. A second hit, after 2 minutes 35 seconds was possibly on the same ship, which sank within seven minutes. After 2 minutes 41 seconds a third hit was heard but not observed.
At 07.40 hours, U-186 fired a spread of two stern torpedoes and heard two detonations on different targets, but only the Eulima was hit, the second detonation being a depth charge from the US Coast Guard cutter USS Spencer.
At 11.30 hours, the drifting wreck of the Eulima was sunk by a coup de grâce and gunfire from U-186.

The master, 52 crew members and nine gunners from the Eulima (Master Frederick William Wickera) were lost. The third officer J. Campkin was taken prisoner by U-186, landed at Lorient on 5 March and taken to the POW camp Milag Nord near Bremen.