In September 1942, Caswell enlisted in the Aviation Cadet Program of the U.S. Navy, and was commissioned a
second lieutenant in the
U.S. Marine Corps and on December 16, 1943, he received his
Wings of Gold at
NAS Pensacola.
World War II In April 1944, after completing additional training, Caswell was assigned to
VMF-221, which was equipped with the
Vought F4U Corsair, at
Santa Barbara, California, before being deployed aboard the aircraft carrier
USS Bunker Hill (CV-17) in the Pacific in January 1945. Caswell and his unit took part in aerial attacks against the
Japanese mainland. On March 18, he scored his first aerial victories when he shot down three
A6M Zeros, while attacking an airfield in
Miyazaki Prefecture. On April 12, 1945, during the
Battle of Okinawa, Caswell scored his fourth aerial victory when he shot down a Zero over
Kikaijima. His biggest day came on April 28 while on a combat air patrol 150 miles north of Okinawa, he shot down a
Kawasaki Ki-61 and his flight was vectored to a formation of 25 Zeros that were headed toward
Task Force 58 and Okinawa. In the ensuing battle, Caswell's flight was credited with destroying eight Zeros, he himself shooting down two of them with the probable destruction of another. For his heroism in the aerial battle, he was awarded the
Silver Star and earned the title of
flying ace. Caswell survived the attack, and he and other surviving airmen helped the firefighters in fighting the fire on the
Bunker Hill. During the war, Caswell was credited with the destruction of seven enemy aircraft in aerial combat, plus one probable destruction. After returning to the United States, Caswell was assigned as an F4U pilot with
VMF-451 at
MCAS El Centro in California, from June 1945 until he left active duty in November 1945. Caswell served in a variety of command and staff positions over the next 15 years, including at
MCAS Beaufort, where he served as commanding officer of
MACS-6, from January to December 1964. His final position was as commanding officer of Headquarters and Service Battalion at
MCRD Parris Island, from April 1966 until his retirement from the Marine Corps on December 31, 1968. ==Later life==