Frank Armstrong was born on March 7, 1930, in Shreveport, Louisiana. He enlisted in U.S. Air Force Preflight Training on October 29, 1952, and then attended Undergraduate Pilot Training, receiving a commission as a 2d Lt and his pilot wings at Greenville AFB, Mississippi, on February 24, 1955. Lt Armstrong completed Pilot Instructor School in July 1955, and then served as an instructor pilot with the 3617th Pilot Training Squadron at Craig AFB, Alabama, until June 1959. He then completed F-100 Super Sabre Combat Crew Training in April 1960, followed by F-100 Operational Training until August 1960. Capt Armstrong served with the 417th Tactical Fighter Squadron at Ramstein AB, West Germany, from September 1960 to April 1963, followed by service as a gunnery instructor at Luke AFB, Arizona, from May 1963 to November 1964. His next assignment was as an instructor pilot back at Ramstein AB from November 1964 to August 1965, followed by service with the 10th Tactical Fighter Squadron at Hahn AB, West Germany, from August 1965 to July 1966. He was a duty officer with the Operations Division of the 7260th Support Group at Lindsey AS, West Germany, from July 1966 to May 1967, followed by service in Southeast Asia with the 1st Air Commando Squadron at Pleiku AB in the Republic of Vietnam. Maj Armstrong flew A-1 Skyraiders in combat from June 1967 until he was shot down by antiaircraft fire and was killed in action in Laos on October 6, 1967. He was also shot down on an earlier mission on July 13, 1967, but was rescued. His remains have never been recovered. Frank Armstrong, III, was the son of Air Force Lieutenant General Frank A. Armstrong, Jr. (1902-1969).

His Silver Star Citation reads:

Major Frank A. Armstrong III distinguished himself by gallantry in connection with military operations against an opposing armed force as an A-1E fighter pilot in the Republic of Vietnam on 6 October 1967. On that date, Major Armstrong led a flight of two Skyraiders flying air cover for helicopters during an insertion. When he observed the lead helicopter taking intense automatic weapons fire from the landing zone, Major Armstrong led his flight on repeated attacks against the gun positions until his aircraft was hit and observed to crash and explode on impact with the ground. By his gallantry and devotion to duty, Major Armstrong has reflected great credit upon himself and the United States Air Force.