After graduation from the Infantry Officer Candidate School Fort Benning, Georgia in May 1967 and the Rotary Wing Officers Course Fort Rucker, Alabama in May 1968, he served as a platoon leader of an Assault Helicopter Platoon in Chu Lai, South Vietnam. He distinguished himself by volunteering for numerous combat missions that were above and beyond the call of duty. While saving numerous lives, he was shot down and rescued three times. For his heroic actions he was awarded 43 Air Medals and 2 Meritorious Service Medals for Valor.
He returned to the United States in 1969 to initially serve as a rotary wing flight instructor Fort Rucker, Alabama, but after a short period was vetted for and selected as the Executive Officer of the largest Student Aviation Company in the world.
He subsequently volunteered to return to South Vietnam in 1970 and served as a Project Officer for the Army Concept Team in Vietnam researching, developing, and testing new combat equipment. Upon returning to the United States he served as an Instructor for the Infantry School Fort Benning, Georgia.
From 1973 to 1978, he completed both a Baccalaureate Degree in Nursing with honors and a Masters Degree in Psychiatric Mental Health Nursing both from the University of South Carolina.
His nursing career traversed numerous leadership positions from Head Nurse, through Director of Nursing to the prestigious position of Chief Nurse, 44th Medical Brigade, Fort Bragg, North Carolina. In this position he deployed to the first Gulf War and Haiti.
From 1966 to his retirement in 2000, Colonel Koehler's military career spanned 34 years of dedicated service to our nation. Along the way he consistently credited his success to family and the men and women that helped him along the way.