to the West Coast Sound Training Squadron, and, until early 1944, she was used primarily as a schoolship. On 25 April 1944, she departed San Diego for Puget Sound and conversion to a high-speed transport. Reclassified APD-25 on 20 May, she returned to San Diego in June; underwent amphibious training, and in July steamed for Hawaii. During late July and early August, she trained with underwater demolition teams (UDT). On 10 August, UDT 10 reported aboard, and on 12 August, Rathburne continued west. After rehearsals in the Solomons, Rathburne sortied from Purvis Bay with TG 32.5 on 6 September. Six days later, she arrived off the Palaus to begin her first combat operations, the Peleliu and Angaur preinvasion bombardment and minesweeping operations. On 14 September she offloaded UDT 10, supported them with gunfire as they cleared the approaches to the Angaur beaches, and reembarked them on 15 September. Rathburne resumed covering fire for UDT 8, after reembarking UDT 10, then on 16 September took up screening duties. On 19 September, she departed Angaur and headed for Ulithi, where UDT 10 reconnoitered the Falalop and Asor beaches, beginning on 21 September. By 23 September the atoll had been occupied and Rathburne moved south, to New Guinea and the Admiralties, to prepare for the invasion of Leyte. On 18 October, the APD entered Leyte Gulf. The next day, UDT 10 went ashore on Red Beach in the northern assault area between Palo and San Ricardo. Through the morning, Rathburne provided covering fire and shortly after noon pulled the team off the beach. On 20 October, she covered the landings, and then shifted to fire support off the Dulag beaches. Detached, soon after her arrival, she began messenger and passenger runs between the northern and southern transport areas. The next day, she transited Surigao Strait en route to Kossol Roads, the Admiralties, the Solomons, and New Caledonia. At the end of November she steamed west, for New Guinea. In December, she prepared for the Luzon offensive. On the 27th, she sailed for Lingayen Gulf. Assigned to TU 77.2.1, the San Fabian fire support group, she acted as part of the antiaircraft screen en route and splashed two enemy planes on 5 January 1945. The following day she was in Lingayen Gulf, screening larger ships bombarding the assault area. On 7 January, she landed UDT 10 on Blue Beach and covered them as they