On 6 December 1941, only one day before the Japanese Attack on Pearl Harbor, Campbell was appointed commanding officer of the Marine Aircraft Group 11 stationed at Brown Field within Quantico Base. He served in this capacity until 25 May 1942, when he was personally selected by Chief of Combined Operations, Lord Mountbatten. Campbell was assigned to this staff as Marine Corps Aviation Officer and his main responsibility was to advise in the matter of Air Cover for Commando operations. He participated in the planning of Dieppe Operation. Campbell served in this capacity until April 26, 1943. For his service in England, he was promoted to the rank of brigadier general and decorated with the Legion of Merit.