Harmon Chadbourn Rorison was born on April 15, 1893 in Wilmington, North Carolina. Rorison served as a private first class and was promoted to first lieutenant with the U.S. Aviation corps in France during World War I. With the permission of the U.S. War Department, Rorison traveled to Poland and Russia, joining the Polish Army as a pilot in the Kosciuszko Aviation Squadron. His plane was shot down and returned to the U.S. with the rank of captain.
During World War II, Rorison volunteered as an ambulance driver with the American Field Service. He was sent overseas in December 1943, and served in the Italian and France-Germany Campaigns with AFS units CM 54 and FR 8-T before returning to the United States in June 1945.