Daniel Hefel was born in 1950 in Guttenberg, Iowa. He enlisted in the U.S. Army on December 4, 1968, and completed basic training and advanced individual training as an infantryman at Fort Polk, Louisiana, in April 1969. CPL Hefel served as an infantryman with Company B, 2nd Battalion of the 501st Infantry in South Vietnam from June 1969 to January 1970, and then as a door gunner on UH-1 Huey helicopters with 2nd Brigade, 101st Airborne Division, in South Vietnam from January 1970 until his helicopter was shot down and he was taken as a Prisoner of War on February 5, 1970. After spending 1,147 days in captivity, Sgt Hefel was released during Operation Homecoming on March 27, 1973. He was hospitalized to recover from his injuries at Fitzsimmons Army Medical Center in Denver, Colorado, from March 1973 until he was medically retired from the Army on May 16, 1974.

His Bronze Star Medal Citation reads:

The President of the United States of America, authorized by Executive Order, August 24, 1962, has awarded the Bronze Star Medal to Sergeant Daniel H. Hefel, United States Army, for meritorious service in ground operations against hostile forces: Sergeant Daniel H. Hefel distinguished himself by meritorious service while held Prisoner of War in Southeast Asia during the period 5 February 1970 to 27 March 1973. His ceaseless efforts to conduct himself strictly in accord with the Code of Conduct and policies of the prisoner organization in the difficult conditions of a communist prison clearly demonstrated his loyalty, love of country and professionalism. By his unselfish dedication to duty, he reflected great credit upon himself and the United States Army.