Frank Cius was born in 1947 in Buffalo, New York. He enlisted in the U.S. Marine Corps on February 18, 1966, and completed basic training at MCRD Parris Island, South Carolina, in May 1966. Pvt Cius next attended Infantry Training at Camp Lejune, North Carolina, from May to July 1966, and then attended Aviation School in Memphis, Tennessee, from August to November 1966. His first assignment was as a CH-46A Sea Knight helicopter mechanic and crew chief with Marine Medium Helicopter Squadron 165 (HMM-165) of Marine Aircraft Group 36 (MAG-36), with the 1st Marine Aircraft Wing from December 1966 until the helicopter he was aboard was shot down over Laos on June 3, 1967. LCPL Cius managed to evade capture for a day and a half before being taken prisoner on June 5, 1967. After spending 2,100 days in captivity, SSgt Cius was released during Operation Homecoming on March 4, 1973. He was briefly hospitalized to recover from his injuries at the Marine Barracks at Naval Base Brooklyn, New York, until he left active duty on December 31, 1973. Frank Cius was medically retired from the Marine Corps on November 1, 1978.

His 1st (of 5) Air Medal Citation reads:

For meritorious achievement in aerial flight as a designated Aerial Gunner in Marine Medium Helicopter Squadron 165 during combat support missions in support of the Republic of Vietnam against the insurgent communist guerrilla forces (Viet Cong) from 2 April 1967 to 11 April 1967. He contributed materially to the success of his squadron. His courage and devotion to duty in the face of hazardous flying conditions were in keeping with the highest traditions of the United States Naval Service.