Homeland protest and perhaps they were smarter than the US.
By March 1972 most of Australia's force was back. Then in December when Whitlam (Labour government) was elected he withdrew the last 150 (approx.) troops. That was the end. :)
By 1972.
Gough Whitlam was elected to be the Prime Minister of Australia by the election of 1972. He made several election promises for example, to abolsih conscription and bring the troops of Australia home from the Vietnam War; this has been believed to be the major key in winning the election after being in opposition for 23 years.
Between 1962 and 1972 about 50,000 Australian servicemen and women served in Vietnam.
3 August 1962 - 2 December 1972 .
Australia was a member of the South East Asia Treaty Organization, as was South Vietnam. SEATO was the pacific alliance that drew together the U.S., Korea, Philippines, and Australia to defend South Vietnam against a take-over by North Vietnam.
All three Australian armed forces and civilian formations were involved in the Vietnam war from 1962 to 1972. The related link lists them.
3 August 1962 - 2 December 1972 .
From 1962 to 1972. For further reading: The Battle of Coral; by Lex McAulay. Published in 1988.
The Vietnam War.
Nixon had been elected to begin withdrawing US troops from Vietnam and to turn over more of the fighting to the South Vietnam government. In 1972, North Vietnam finally realized that the war was a stalemate. The two sides met and arranged a cease fire. In January of 1973 the Paris Accords went into effect. The US agreed to withdraw all its troops from Vietnam in 60 days. Congress had stopped funding the war effort. The North Vietnamese government agreed to release all prisoners, which they never did. Free elections were to be held in Vietnam. The President of South Vietnam considered the agreement between North Vietnam and the US as a sell out. But it allowed President Nixon to save face and bring the soldiers home. By 1975, after US troops had been pulled out of South Vietnam, the ARVN (Army of the Republic of South Vietnam) collapsed and the North Vietnamese moved into Saigon, ending the war and finalizing the take over of the South by the North.
All American troops, except for approximately 16,000 military advisors, withdrew from Vietnam on November 30, 1972 ending all combat operations.