In September 1944, Admiral Raymond A. Spruance, the Commander of United States Fifth Fleet, chose Davis as his chief of staff after Admiral Ernest King, the Chief of Naval Operations, ordered that all commanders with a surface warfare background have a chief of staff with aviation experience and vice versa. Davis won over Spruance with his competence and congeniality and was described as a "lean, rough, aggressive leader" who "moved decisively and intelligently." Davis was with the Fifth Fleet until July 1945, and during his tour the fleet operated in the Pacific Ocean against Japanese forces in the Iwo Jima and Okinawa campaigns. He then became the commander of Carrier Division Five.