In late 1942, Coulter's request to join the submarine service was granted and he was assigned to the Navy Submarine School in New London, CT. Upon graduation, he joined the crew of the submarine USS Skipjack in the Pacific Theatre. During his 42 months aboard the Skipjack, he served as Torpedo and Gunnery Officer and later, as Executive Officer. In March 1944, he was promoted to Lieutenant Commander and assumed command of the Skipjack, a position he held for 20 months.
