 In March 1966, he deployed with the 1st Cavalry Division to An Khe which is located in the Central Highlands of South Vietnam.He undertook two years of airborne infantry reconnaissance work in Vietnam before he was first assigned to an Army Special Forces unit, the 5th Special Forces Group in Vietnam.Miller also became a member of the elite and highly-secretive Military Assistance Command, Vietnam - Studies and Observations Group (MAC-V SOG).