In October 1940 he was given command of a "Dido"-class light cruiser, HMS "Hermione" then under construction on the Clyde. The ship worked up at Scapa Flow and as part of the Second Cruiser Squadron took part in the May 1941 hunt for the "Bismarck". The ship was then assigned to Force H based at Gibraltar on convoy duties to relieve Malta. The ship rammed the Italian 600-Serie "Adua " submarine "Tembien" near Tunis on 2 July 1941, for which Oliver was awarded a Distinguished Service Order (DSO) in November.