Yet with the Phuoc Tuy province coming progressively under control throughout 1967 , the Australians increasingly spent a significant period of time conducting operations further afield . 1 ATF was subsequently deployed astride infiltration routes leading to Saigon to interdict communist movement against the capital as part of Operation Coburg during the 1968 Tet Offensive and later during the Battle of Coral – Balmoral in May and June 1968 . At Fire Support Bases Coral and Balmoral the Australians had clashed with regular North Vietnamese Army and Viet Cong main force units operating in battalion and regimental strength for the first time in near conventional warfare , ultimately fighting their largest , most hazardous and most sustained battle of the war . During 26 days of fighting Australian casualties included 25 killed and 99 wounded , while communist casualties included 267 killed confirmed by body count , 60 possibly killed , 7 wounded and 11 captured . Other significant Australian actions included Binh Ba in June 1969 , Hat Dich in late @-@ December 1968 and early 1969 and Long Khanh in June 1971 . At the height of the Australian commitment , 1 ATF numbered 8 @,@ 500 troops , including three infantry battalions , armour , artillery , engineers , logistics and aviation units in support . A third RAAF unit , No. 2 Squadron RAAF , flying Canberra bombers , was sent in 1967 , and four RAN destroyers joined US patrols in the waters off North Vietnam .