What role did Australia play in the Vietnam War?
It played an active role and is the longest conflict the country was ever involved in
The Vietnam War was the longest twentieth century conflict in which Australians participated ; it involved some 60,000 personnel and grew from a limited initial commitment of 30 military advisers in 1962 to include a battalion in 1965 and finally, in 1966, a task force. Each of the three services was involved, but the dominant role was played by the Army.
After the cessation of combat operations in 1972, a limited number of Australian personnel remained in Vietnam, and elements of the RAAF returned in 1975, carrying out evacuations and assisting refugees almost until the moment of South Vietnam's surrender.
Source and more details:http://vietnam-war.commemoration.gov.au/vietnam-war/index.php