After Okinawa was secured, the Third Fleet concentrated on operations against Japan itself. From 10 through 29 July 1945, "Merrimack" supported raids of overwhelming force on Japanese targets which hastened the end of the war. Following Japan's capitulation on 15 August 1945, "Merrimack" made several cruises between the United States West Coast and East Asia bringing oil for ships supporting the occupation of Japan and operating along the coasts of China and Korea. She was assigned to Military Sea Transportation Service (MSTS) in October 1949, shortly before beginning pre-inactivation overhaul. "Merrimack" was decommissioned on 8 February 1950 and entered the Atlantic Reserve Fleet at Orange, Texas.