In January 1943, he attended diesel engineering school for sixteen weeks before being assigned to First Naval District, Boston in May. Muskie worked on the for a month. In June he was assigned to the at Fort Schuyler in New York where he worked as an indoctrinator. In November 1943 he was promoted to Deck Officer. He trained for two weeks in Miami, Florida at the Submarine Chaser Training Center. After that he was relocated to Columbus, Ohio to study reconnaissance in February 1944. In March, he was promoted to Lieutenant (junior grade). Muskie was stationed at California's Mare Island in April temporarily before formally engaging in active duty warfare.