Although individual members of the regiment had served as advisors with the Australian Army Training Team Vietnam (AATTV) since 1962, it was not until April 1965 that the government announced that a battalion would be deployed to Vietnam. Between June 1965 and March 1972 the units of the regiment would conduct sixteen rotations in Vietnam, with the first seven battalions completing two 12-month tours, while 8 and 9 RAR would each serve one. Consequently, following a period of hurried training and administration 1 RAR joined the US 173rd Airborne Brigade at Bien Hoa airbase outside of Saigon in June 1965. After initially defending the airbase, 1 RAR steadily increased the scope of its patrols. For example, in January 1966, 1 RAR assaulted a large Viet Cong headquarters complex in the Ho Bo Woods as a part of Operation Crimp; which the Americans hailed as the first strategic intelligence victory of the war. The battalion subsequently completed a 12-month-tour attached to US forces, during which it developed new tactics and techniques that later became standard for Australian battalions and supporting arms and services that would subsequently operate in Vietnam.