Mark Ruhling was born on August 18, 1940, in Pittsburgh, Pennsylvania. After attending Penn State University for three years, he enlisted in the Aviation Cadet Program of the U.S. Air Force for Navigator training on March 2, 1962, and was commissioned a 2d Lt in the U.S. Air Force and awarded his Navigator wings at James Connally AFB, Texas, on July 23, 1963. Lt Ruhling next attended Navigator/Bombardier training at Mather AFB, California, from August 1963 to May 1964, followed by Advanced Survival Training, Navigator-Bombardier Upgrade Training, and B-52 Stratofortress Combat Crew Training at Castle AFB, California, from May to October 1964. His first assignment was as a B-52 Navigator with the 6th Bomb Squadron at Clinton Sherman AFB, Oklahoma, from October 1964 to May 1967, and he then attended Navigator Reconnaissance Upgrade training from July to September 1967. Capt Ruhling attended RF-4C Phantom II Tactical Reconnaissance Upgrade training from September 1967 to April 1968, and then deployed to Thailand in May 1968, where he served as an RF-4C Reconnaissance Systems Operator with the 14th Tactical Reconnaissance Squadron at Udorn Royal Thai AFB, Thailand, from June 1968 until he was forced to eject over North Vietnam and was taken as a Prisoner of War on November 23, 1968. After spending 1,573 days in captivity, Capt Ruhling was released during Operation Homecoming on March 14, 1973. He was briefly hospitalized to recover from his injuries at Wright Patterson AFB, Ohio, and then received an Air Force Institute of Technology assignment to complete his bachelor's degree at Southwestern State College in Weatherford, Oklahoma, from August 1973 to May 1974. Maj Ruhling next attended the Defense Intelligence School in Washington, D.C., from May 1974 to June 1975, followed by service as an Intelligence Officer with the Defense Intelligence Agency in Washington, D.C., from June 1975 to June 1977. He attended Air Command and Staff College at Maxwell AFB, Alabama, from June 1977 to June 1978, and then served as an RF-4C Reconnaissance Systems Operator and Flight Commander with the 91st Tactical Reconnaissance Squadron at Bergstrom AFB, Texas, from June 1978 to June 1979. Lt Col Ruhling's final assignment was as a Wing/Base Officer Controller with the 67th Tactical Reconnaissance Wing at Bergstrom AFB from June 1979 until his retirement from the Air Force on November 1, 1982.

His Distinguished Flying Cross for Valor Citation reads:

Captain Mark J. Ruhling distinguished himself by heroism while participating in aerial flight as an RF-4C navigator over North Vietnam on 13 August 1968. On that date Captain Ruhling's skill and persistence were paramount in obtaining the assigned military objective in the presence of hostile action. To successfully accomplish the objective, this aviator subjected himself to continuous deadly antiaircraft, missile, and MIG threats through the most heavily defended area of North Vietnam. The outstanding heroism and selfless devotion to duty displayed by Captain Ruhling reflect great credit upon himself and the United States Air Force.