In March 1966, Prime Minister Harold Holt announced that Australia would increase its commitment to Vietnam. In May 1966 the newly raised 5 and 6 RAR arrived in theatre as a part of the 1st Australian Task Force (1 ATF) in Phuoc Tuy Province, establishing a base at Nui Dat. After two months of constant patrolling by both battalions, 6 RAR was engaged in the action that would become a defining part of the regiment's war in Vietnam; the Battle of Long Tan. Fought on 18 August 1966, 108 men from D Company, 6 RAR fought a ferocious meeting engagement with the Viet Cong 275th Regiment, possibly reinforced by at least one North Vietnamese battalion, and D445 Battalion (between 1,500 and 2,500 personnel). After fighting for two and a half hours, D Company was surrounded on three sides. However, with the assistance of strong artillery support they were able to hold their position until the timely arrival of a relief force of infantry and armoured personnel carriers (APCs) finally forced the Viet Cong to break. In the words of the official historian, Ian McNeill, "D Company had achieved a stunning victory".