Colonel Heffelfinger was commissioned an Infantry Officer upon graduation from Officer Candidate School, 29 April 1947, class number 3.  His first duty assignment was as Classification & Assignment Officer, Headquarters, 3rd Armd Division, Fort Knox, Kentucky. | His subsequent duty assignment include: Chief, Classification & Assignment Division, Headquarters, 101st Abn Div, Camp Breckinridge, Kentucky; Chief, Dependent Travel Branch, Headquarters, Eight Army, Yokohama, Japan; Chief, Off Chief & Headquarters Pers Br, Headquarters EUSAK, Korea; Asst Adjutant General, General Headquarters, FECOM, Japan; Assistant Adjutant, 2112 ASU, Carlisle Barracks, Pennsylvania; Personnel Staff Officer, 2141 SU, Fort Ritchie, Maryland; Assistant Chief, Prom Unit, Res Branch, DA, TAGO, Washington, D.C.; S-2 and S-3, Headquarters, 1st Bn, 30th Inf, 3d Inf Div, Fort Benning, Georgia; Corps Finance Officer, Headquarters, VII Corps, Germany; Dep Army Finance Officer, Headquarters, Seventh Army, Germany; Chief, 3d USA Cen Fin Officer, Fort McPherson, Georgia; Executive Officer to D.C.S, Comptroller, Headquarters, Third Army, Georgia; Fin & Acctg Off, Headquarters, U.S. Army, Hawaii; Chief, Management & Anal Div, Comptroller, Headquarters, U.S. Army, Hawaii; Chief, Fin Affairs Division, Comptroller, Headquarters, USMACV. | Colonel Heffelfinger's awards and decorations include: Army Commendation Medal w/1 Oak Leaf Cluster; Air Medal; Bronze Star Medal.