Answer by taking a quote from the following article:

Edward Leo Peter McMahon Jr. (March 6, 1923 - June 23, 2009) was an American announcer, game show host, comedian, actor and singer. McMahon and Johnny Carson began their long association in their first TV series, the ABC game show Who Do You Trust?, running from 1957 to 1962. Then afterwards, McMahon would make his famous thirty-year mark as Carson's sidekick, announcer and second banana on NBC's highly successfully The Tonight Show Starring Johnny Carson from 1962 to 1992.

McMahon hoped to become a United States Marine Corps fighter pilot. Prior to the US entry into World War II, however, both the Army and Navy required two years of college for their pilots program. McMahon enrolled into classes at Boston College and studied there from 1940 to 1941. On The Howard Stern Show in 2001, McMahon stated that after Pearl Harbor was attacked, the college requirement was not lifted and he still had to finish his two years of college before applying for Marine Corps flight training.  After completing the college requirement, McMahon was able to enlist as he previously wished. His primary flight training was in Dallas, followed by fighter training in Pensacola, where he also earned his carrier landing qualifications. He was a Marine Corps flight instructor in F4U Corsairs for two years, finally being ordered to the Pacific fleet in 1945. However, his orders were canceled after the atomic bomb was dropped on Hiroshima and Nagasaki, forcing Japan's surrender unconditionally.  As an officer in the reserves, McMahon was recalled to active duty during the Korean War. This time, he flew the OE-1 (the original Marine designation for the Cessna O-1 Bird Dog), an unarmed single-engine spotter plane. He functioned as an artillery spotter for the Marine batteries on the ground and as a forward controller for the Navy and Marine fighter bombers. He flew a total of 85 combat missions, earning six Air Medals. After the war, he stayed with the Marines as a reserve officer, retiring in 1966 as a colonel. In 1982, McMahon received a state commission as a brigadier general in the California Air National Guard, an honorary award to recognize his support for the National Guard and Reserves.

Was he wounded in service?
his orders were canceled after the atomic bomb was dropped on Hiroshima and Nagasaki,