On 11 August, "Marsh" detached from the Expeditionary Force, and sailed for Okinawa. Resuming escort duties, she steamed back to the Marianas and then on to Tokyo. Departing Tokyo on 31 August, she sailed for Pearl Harbor, arriving there on 24 September. Then she took on equipment which transformed her into a mobile power unit. In this conversion, an electric generator and power cables replaced her torpedo tubes. With this new asset, she returned to Guam on 26 October to provide ship-to-shore power services until the end of the year.