In April 1937, Litchfield, as part of the Battle Fleet, changed her permanent base from the west coast to Pearl Harbor. On 20 May she became flagship of Submarine Squadron 4, Submarine Force, Pearl Harbor, and continued to operate with submarines as war approached and training drills intensified during 1941. With the outbreak of war in the Pacific, Litchfield's duties involved the escort of U.S. submarines both in and out of port and anti-submarine patrol off the entrance to Pearl Harbor.