The oiler sailed for Pearl Harbor on New Year's Day, 1944, and remained there until 16 January when she sortied with Task Group (TG) 58.1 for operations supporting the occupation of the Marshall Islands. "Ashtabula" anchored at Majuro lagoon on 4 February and operated from that atoll in support of the fast carrier task forces through mid June. The ship then began participating in the effort to take the Marianas. During the Battle of the Philippine Sea and its aftermath, she fueled ships of Task Force 58 (TF 58) from 20 through 27 June and then retired, via Eniwetok, to the California coast for yard work which began upon her arrival at Terminal Island on 15 July.