DeWitt saw duty on Luzon from July to September 1945 as Chief of Supply, Marine Corps Section, U.S. Army Forces, Western Pacific, in connection with advanced planning with the army for the intended invasion of Japan.
He returned to the United States in February 1946 and was appointed Officer-in-Charge of the Supply Division, Depot of Supplies, Philadelphia.
He served under Brigadier General Leonard E. Rea and was selected for integration into the Regular Marine Corps in July 1946.

He was transferred to Camp Pendleton in July 1946 and assumed command of Supply Depot there.
DeWitt was ordered to the Naval War College at Newport, Rhode Island, in July 1952 and completed a course in strategy and logistics one year later.
He was subsequently transferred to Washington, D.C., and attached to the Supply Department at Headquarters Marine Corps.
DeWitt served as assistant to the executive officer of the supply department and was promoted to brigadier general on July 1, 1956.

DeWitt assumed his final assignment as commanding general of Marine Supply Center Barstow in February 1957.
In this capacity, he commanded 2,300 civilian personnel and 1,300 Marines and was responsible for the supplying of all Marine Forces West of Mississippi River.
His command handled the maintenance of physical facilities and provided approximately 840 pieces of motorized vehicles, including trucks and warehouse equipment.
Further, his Repair Division of the center provided repair services and overhaul for LVTs, tanks, buses and trucks.
DeWitt saw duty on Luzon from July to September 1945 as Chief of Supply, Marine Corps Section, U.S. Army Forces, Western Pacific, in connection with advanced planning with the army for the intended invasion of Japan. He returned to the United States in February 1946 and was appointed Officer-in-Charge of the Supply Division, Depot of Supplies, Philadelphia. He served under Brigadier General Leonard E. Rea and was selected for integration into the Regular Marine Corps in July 1946.
He was transferred to Camp Pendleton in July 1946 and assumed command of Supply Depot there. DeWitt was ordered to the Naval War College at Newport, Rhode Island, in July 1952 and completed a course in strategy and logistics one year later. He was subsequently transferred to Washington, D.C., and attached to the Supply Department at Headquarters Marine Corps. DeWitt served as assistant to the executive officer of the supply department and was promoted to brigadier general on July 1, 1956.
DeWitt assumed his final assignment as commanding general of Marine Supply Center Barstow in February 1957. In this capacity, he commanded 2,300 civilian personnel and 1,300 Marines and was responsible for the supplying of all Marine Forces West of Mississippi River. His command handled the maintenance of physical facilities and provided approximately 840 pieces of motorized vehicles, including trucks and warehouse equipment. Further, his Repair Division of the center provided repair services and overhaul for LVTs, tanks, buses and trucks.
Ralph B. DeWitt