He then joined 5th Marine Regiment, 1st Marine Brigade under Brigadier General Holland Smith and was promoted to first lieutenant in summer 1940. Hittle remained with the unit following its expansion to 1st Marine Division and participated in the amphibious exercise at Culebra, Puerto Rico. He assumed command of the Marine detachment aboard the battleship USS "Washington" in May 1941 and participated in the Arctic convoys in the Norwegian Sea in April 1942. During his service aboard that ship, he was promoted to captain in February 1942.