In July 1940, Vanquisher returned to convoy defence duties with the 11th Destroyer Flotilla, and on 8 July 1940 she and the destroyer HMS Scimitar H21 2 rescued 43 survivors of the British merchant ship Humber Arm, which the German submarine U-99 had torpedoed and sunk in the North Atlantic 60 nautical miles south of Fastnet Rock, Ireland, at coord.