 Based at Nui Dat in the III Corps Tactical Zone as part of US II Field Force , Vietnam , 1 ATF now included two infantry battalions plus armour , aviation , engineers and artillery support , with total Australian troop strength in Vietnam reaching 6 @,@ 300 men . Logistic arrangements were provided by the 1st Australian Logistic Support Group based at the port of Vung Tau . The 5th and 6th Battalions , Royal Australian Regiment ( 6 RAR ) subsequently returned to Australia in May and June 1967 , and were replaced by the 2nd and 7th Battalions , Royal Australian Regiment ( 7 RAR ) . Meanwhile , Viet Cong units operating in the province in early 1967 included Main Forces from the Viet Cong 5th Division , which consisted of the 274th Regiment and 275th Regiment , each of three infantry battalions under the command of Senior Colonel Nguyen The <unk> . Supporting this force were a number of artillery , engineer , medical and logistic units . Group 89 ( Artillery ) was equipped with recoilless rifles , medium mortars and heavy machine @-@ guns . Local Forces included D445 Provincial Mobile Battalion , a provincial unit normally operating in the south of the province and in Long Khanh , while guerrilla forces included two companies in the Chau Duc district , one in Long Dat and a platoon in Xuyen Moc ; in total around 4 @,@ 500 men . 
