The Battle of Long Tan (18 August 1966) took place in a rubber plantation near Long Tan, in Phuoc Tuy Province, South Vietnam during the Vietnam War. The action was fought between Australian forces and Viet Cong and North Vietnamese units after 108 men from D Company, 6th Battalion, Royal Australian Regiment (6 RAR) clashed with a force of 1,500 to 2,500 from the Viet Cong 275th Regiment, possibly reinforced by at least one North Vietnamese battalion, and D445 Provincial Mobile Battalion. The 1st Australian Task Force (1 ATF) had arrived between April and June 1966, constructing a base at Nui Dat. After two months it had moved beyond the initial requirements of establishing itself and securing its immediate approaches, beginning operations to open the province. Meanwhile, in response to the threat posed by 1 ATF the 275th Regiment was ordered to move against Nui Dat. For several weeks Australian signals intelligence had tracked a radio transmitter moving westwards to a position just north of Long Tan; however, extensive patrolling failed to find the unit. At 02:43 on the night of 16/17 August, Viet Cong mortars, recoilless rifles (RCLs) and artillery heavily bombarded Nui Dat from a position to the east, before being engaged by counter-battery fire. The following morning B Company, 6 RAR departed Nui Dat to locate the firing points and the direction of the Viet Cong withdrawal. A number of weapon pits were subsequently found, as were the positions of the mortars and RCLs.