Mack then returned to "Jervis", to serve as Captain (D) of the 14th Destroyer Flotilla in the Mediterranean Fleet, and was awarded the Distinguished Service Order on 11 July 1940. After leading his flotilla in the Battle of the Tarigo Convoy on 16 April 1941 he received a bar to his DSO on 1 August 1941, and for his part in the Battle of Cape Matapan in late March 1941 he received a second Mention in Despatches on 3 February 1942.