In August 1966, Badcoe arrived in South Vietnam as a member of the Australian Army Training Team Vietnam. He was initially a sub-sector adviser, but in December became the operations adviser for Thừa Thiên-Huế Province. In this role, between February and April 1967, he displayed conspicuous gallantry and leadership on three occasions while on operations with South Vietnamese Regional Force units. In the final battle, he was killed by a burst of machine-gun fire. He was highly respected by both his South Vietnamese and United States allies, and was posthumously awarded the Victoria Cross for his actions. He was also awarded the United States Silver Star and several South Vietnamese medals. He was buried at Terendak Garrison Cemetery in Malaysia.