On 10 July,
Mascoma departed Ulithi to rendezvous with units of
task group TG 38.1, then involved in attacks on the Japanese home islands. She returned to Ulithi on 1 August, replenished her supplies and was underway again by the 8th. On the 9th engine trouble once again forced
Mascoma to drop out of formation. Ordered to
Saipan, she was unable to rejoin her task group until the 20th, by which time hostilities had ended. She continued fueling at sea operations until the 28th, when she steamed for
Japan. In Japan she carried out harbor fueling assignments at
Sagami Wan, before proceeding to
Tokyo Bay, she was the first ship in the harbor after Japan surrendered, as she was the closest ship at the time, where she witnessed the official surrender on 2 September. The next day, 3 September, she returned to Ulithi for fueling assignments and, again, repairs to her boilers. On 24 October, the oiler departed for the
United States, arriving on 26 November at
Norfolk, Virginia, where she decommissioned on 17 December. Struck from the
Naval Vessel Register on 8 January 1946, she was transferred to the
Maritime Commission on 27 June 1946. Returned to the Navy, she was accepted by the
3rd Naval District and reactivated on 4 February 1948. In August 1949 she was berthed at
Orange, Texas, as a unit of the
Atlantic Reserve Fleet, but was reactivated again on 27 July 1950. == Supporting the Korean War effort ==