In June 1961, Badcoe was posted to the 103rd Field Battery as battery captain, and served a tour with them in the Federation of Malaya in the aftermath of the Malayan Emergency. He was detached from Malaya to South Vietnam over the period 7–14 November 1962, and observed how that country was combating the Viet Cong (VC) and North Vietnamese insurgency. During his visit, Badcoe sought opportunities to experience combat. He spent five days with an Army of the Republic of Vietnam (ARVN) battalion on operations in Quảng Ngãi Province, during which the unit had contacts with the enemy, including a pitched battle. During what was supposed to be a rest period, he arranged a helicopter flight to visit a Montagnard base in the Central Highlands. When his return to Malaya was delayed by an aircraft engine breakdown, he managed to join a heliborne operation of the 7th ARVN Division in the Mekong Delta. He returned to the 1st Field Regiment in November 1962 and remained with the unit until August 1965. At this point, Badcoe transferred from the artillery to the Royal Australian Infantry Corps, and on promotion to temporary major on 10 August 1965, was posted to the Infantry Centre at Ingleburn, New South Wales. Badcoe successfully applied for a posting with the Australian Army Training Team Vietnam (AATTV), and attended adviser courses at the Intelligence Centre at Mosman, New South Wales, and Jungle Training Centre in Canungra, Queensland. He was promoted to provisional major in June 1966.