Colonel Earnest Lynn Hepler Jr. was commissioned an Engineer Officer upon graduation from Engineer Officer Candidate School class 107-66 at Fort Belvoir, Virginia on 30 September, 1966.  His first duty assignment was as a Rotary Wing Aviator, 336th Assault Helicopter Company, Soc Trang, Vietnam.

His notable duty assignments include: Chief Audiology Clinic, Walson Army Hospital, Fort Dix, New Jersey; Chief, Audiology Clinic, 97th General Hospital, Frankfurt, West Germany; Assistant Director, Army Audiology & Speech Center, Walter Reed Army Medical Center, Washington D.C.; Chief, Audiology & Speech Clinic, 2nd General Hospital, Landstuhl, West Germany; Chief, Occupational Health and Epidemiology Branch, 10th Medical Laboratory, Landstuhl, West Germany; Chief, Bio Acoustics Division, US Army Environmental Hygiene Agency, Aberdeen Proving Ground, Maryland; Director of Radiation and Entomological Sciences, US Army Environmental Hygiene Agency, Aberdeen Proving Ground, Maryland; and Chief of Staff, United States Army Environmental Hygiene Agency, Aberdeen Proving Ground, Maryland. His last duty assignment was served as the Brigade Commander, Uniformed Services University of the Health Sciences, Bethesda, Maryland.

His military education includes: Rotary Wing Warrant Officer Aviator Course, Engineer Officer Candidate School, Aircraft Maintenance Officers Course, University of Florida, Medical Department Officer Advanced Course, Command and General Staff Officer Course, Senior Officers Legal Course.

His highest military awards include: Defense Superior Service Medal, Legion of Merit (2^nd Award), Bronze Star Medal, Meritorious Service Medal (4^th Award),  Air Medal w/ “V” Device, Air Medal (15^th Award), Army Commendation Medal with “V” Device, Army Commendation Medal (2^nd Award), Republic of Vietnam Campaign Medal,  Army Superior Unit Award, Army Aviator Badge.