After shakedown along the California coast, Gwin sailed for the Pacific theatre as flagship of Mine Squadron 3, reaching Pearl Harbor 3 January 1945. A week later the squadron left for the fighting front. At Saipan, 20 January, Gwin and her sister minesweepers joined Battleship Division 7. For 7 days, 21 to 26 January, she participated in the preliminary bombardment of Iwo Jima, next to the last step in the island-hopping campaign across the Pacific. Returning to Pearl Harbor, Gwin underwent overhaul before sailing for Eniwetok, 23 February.
