Theodore Gamlin was born in December 1948 in Ayer, Massachusetts, and grew up in Groton, Massachusetts. He enlisted in the U.S. Air Force on September 28, 1967, and after completing basic training at Lackland AFB, Texas, he was trained as a Ground Radio Operator. Sgt Gamlin deployed to Southeast Asia in December 1968, and served with the 21st Tactical Air Support Squadron at Nha Trang AB, South Vietnam, from December 1968 to January 1970. During this time he deployed to South Korea during part of 1969. His next assignment was with the 341st Combat Support Group at Malmstrom AFB, Montana, from January 1970 until he received an honorable discharge from the Air Force on August 20, 1971.

His Air Force Cross Citation reads:

The President of the United States of America, authorized by Section 8742, Title 10, United States Code, awards the Air Force Cross to Sergeant Theodore R. Gamlin for extraordinary heroism in military operations against an opposing armed force in the Republic of Vietnam, as a Ground Radio Operator, on 25 October 1969. On that date, while under heavy hostile mortar attack, and in dense ground fog, Sergeant Gamlin utilized his radio equipment to obtain assistance for wounded Allied personnel. Despite his own wounds, he made his way to an unsecure landing zone where he fully exposed himself to possible enemy fire in order to light the landing area for a rescue helicopter. After carrying the wounded men to the helicopter, he refused evacuation so he could further assist in the camp defense during the night. Through his extraordinary heroism, superb airmanship, and aggressiveness in the face of the enemy, Sergeant Gamlin reflected the highest credit upon himself and the United States Air Force.