support the fleet in 1925. She departed Honolulu, Hawaii, on 1 July 1925 with the battle fleet and accompanied it on a voyage across the Pacific Ocean to Australia and New Zealand and then back to San Pedro, where she arrived with the fleet on 26 September 1925. In the late 1920s, Medusa stepped outside her normal repair duties to play a transport role. On 11 May 1927 she departed San Pedro carrying seven officers and 78 enlisted men of the U.S. Marine Corps's Marine Observation Squadron 4 and their six Boeing O2B-1 aircraft to Nicaragua. In July 1928, she again carried Marines to Nicaragua, this time in company with storeship . Medusa continued her fleet support duties out of San Pedro until mid-August 1941, when she moved to Pearl Harbor, Hawaii. She was there on 7 December 1941 when Imperial Japanese Navy carrier aircraft attacked. With her commanding officer ashore, her repair officer, Lieutenant Commander John F. P. Miller, took command. Medusa fired on a Japanese Type A midget submarine she sighted in the harbor, ceasing fire on it when destroyer closed in to sink the submarine. Medusas antiaircraft machine gunners claimed two Japanese Aichi D3A1 dive bombers shot down during the attack. After the attack, she went to work in her primary role as a repair ship; she provided pumps to the damaged seaplane tender , machine gun ammunition to the grounded battleship , and rifles to U.S. Army troops at Schofield Barracks, and food, beverages, and fuel to ships' boats that visited her, and she assisted in efforts to rescue men trapped in the hull of the capsized antiaircraft training ship . On 1 March 1942, the Base Force was redesignated the Service Force, Pacific Fleet. Now a Service Force unit, Medusa continued to aid the clean-up at Pearl Harbor. On 4 April 1943, Medusa got underway for the combat area. She arrived at Havannah Harbor at Efate in the New Hebrides on 20 April 1943, relieving repair ship there on 24 April 1943. She operated at Efate for the next 11 months, temporarily deploying to Espiritu Santo from 24 July 1943 to 4 August 1943 to fashion a temporary bow for the torpedoed light cruiser . On 27 March 1944, Medusa departed Efate for a series of shorter assignments. First sailing to New Guinea, she repaired ships of the 7th Fleet at Milne Bay and Buna