Conscription in Australia In 1964 compulsory national service for 20-year-old males was introduced under the National Service Act 1964. The selection of conscripts was made by a sortition or lottery draw based on date of birth, and conscripts were obligated to give two years' continuous full-time service, followed by a further three years on the active reserve list. The full-time service requirement was reduced to 18 months in October 1971.
The Defence Act was amended May 1964 to provide that national servicemen could be obliged to serve overseas, a provision that had been applied only once before, during World War II ... During the late 1960s, domestic opposition to the Vietnam War and conscription grew in Australia. (read on)

Concerning a Conscript's Death in Vietnam, Singabout, Journal of Australian Folksong 6(1), 1966, page 19
Another anonymous contribution that arrived in the form of a broadside from Melbourne

Come all you Sons and Daughters of this rich wide Land,
Lift up your voices and lift up your Hands,
They are selling this country to America and then,
They are sealing the Bargain with conscripted men.

The first Australian Conscript is barely one day dead,
When H.M.A.S. Sydney goes sailing through The Heads,
With four hundred more, four hundred more,
To murder and be murdered for the Madmen who want War.

We did not know the dead Man, We knew he once drew Breath
We know Nobody's Freedom was paid for with his Death,
And how many more, how many more,
Will murder and be murdered for the Madmen who want War?

There's a Man with a Smile who Sympathy extends,
To all the grieving Relatives and all the grieving Friends,
In this Nation's highest interest, he says the Conscript died,
We are shamed by his Death, We are shamed by the Man who died.

Errol Wayne Noack, 24th May 1966

HMAS Sydney was based at Garden Island Naval Base in Sydney & made 25 voyages to Vietnam between 1965 and 1972.