Lee Cornwell was born on August 5, 1944, in Richmond, Virginia. He was commissioned a 2d Lt in the U.S. Air Force through the Air Force ROTC program on May 31, 1967, and went on active duty beginning June 12, 1967. Lt Cornwell next completed Undergraduate Pilot Training and was awarded his pilot wings at Williams AFB, Arizona, in June 1968, followed by F-4 Phantom II Combat Crew Training and Pilot Systems Operator Training from October 1968 to April 1969. His first assignment was as an F-4 pilot with the 478th Tactical Fighter Squadron at Homestead AFB, Florida, from May 1969 to October 1970, and then as an F-4 pilot with the 309th Tactical Fighter Squadron at Homestead from October 1970 until he deployed to Southeast Asia in February 1971. Capt Cornwell served as an F-4 Pilot Systems Operator with the 13th Tactical Fighter Squadron of the 432nd Tactical Reconnaissance Wing at Udorn Royal Thai AFB, Thailand, from February 1971 until he was killed in action over Laos on September 10, 1971. He was officially listed as Missing in Action until declared dead on September 28, 1973. His remains were returned to the United States on August 31, 1994, and he was buried at Arlington National Cemetery.

His Distinguished Flying Cross Citation reads:

Captain LeRoy J. Cornwell III distinguished himself by extraordinary achievement while participating in aerial flight as an F-4D Pilot Systems Operator over hostile territory on 8 September 1971. On that date, Captain Cornwell, flying as a fast-moving Forward Air Controller, directed two flights of Tactical Fighters which struck a heavily defended hostile truck park and storage area. Captain Cornwell's expert control and direction resulted in the complete destruction of this highly important target complex, thereby denying its use to the hostile forces. The professional competence, aerial skill, and devotion to duty displayed by Captain Cornwell reflect great credit upon himself and the United States Air Force.