 During World War II, Dwyer served as a 5-inch battery and machine gun officer with the Marine detachment aboard the USS "South Dakota" in both the European Theater of Operations and the Pacific Theater, participating in four major naval campaigns.After his sea duty, he became a tank instructor at Camp Pendleton, California.Immediately following the war, Dwyer returned to Hawaii as the commanding officer of the Marine Barracks, Naval Air Station (NAS) Kaneohe Bay and then at the Naval Air Facility (NAF) Johnson Islands (Pacific Ocean).