Two tours of Vietnam were completed by 1 RAR during the Vietnam War, the first one being between March 1965 and June 1966 and the second between April 1968 and February 1969. In March 1965 advanced elements of 1 RAR deployed for Vietnam by charter aircraft, whilst the rest of the battalion followed later on HMAS Sydney. The battalion arrived at Bien Hoa air base in June and was placed under command of the US 173rd Airborne Brigade, becoming the first Australian unit to serve in an American formation. Initially, the Australian contingent was restricted only to providing security to the airbase, however, these limitations were later removed by the Australian government and in September 1965 began conducting offensive operations against the Viet Cong (VC) including search and destroy missions, security operations and conducting fighting patrols around the Bien Hoa area of operations.