The next day, I dragged myself off to a post office and dropped a form into the slot.

It was my registration for national service.

Conscription, they called it.

The lottery that no one wanted to win.

A few months later the lottery was drawn on TV. Marbles out of a barrel. I was born on the 22nd of my month. The numbers came out for the 21st and the 23rd.

I'd missed the call-up, but the celebration felt hollow.

I was opposed to conscription, though I wasn't a conscientious objector. My objection was political. The call-up was for men aged 20. You didn't get a vote until you were 21. You had no say.

The courageous thing might have been to refuse to register. Let the police come for you like a few of my mates had done. Risk jail.

Still, we all had the same chance of being called up. Didn't we?

The first "nashos", as the lottery winners were known, were marched into camp 50 years ago.

All these years later, we're still arguing about it.

It's hardly surprising: 200 national servicemen, pressed into service by their government, died in Vietnam.

This was way out of proportion to their numbers. Nashos made up just 30 per cent of the near 62,000 Australians who served in Vietnam. But they made up almost 40 percent of the 520 who died. And they accounted for about 60 per cent of those wounded.

But what if the ballot itself had been a fraud?

One of those whose number came up and who was sent to Vietnam, no less than the former deputy prime minister Tim Fischer, is about to air his suspicion that the call-up ballot - or parts of it - was rigged.

Fischer, who concedes his concerns are no more than a hunch, has earned his voice in this matter. As a platoon commander based at Nui Dat, he almost died in Operation Fire Support Base Coral near the southern exit to the Ho Chi Minh Trail in 1968.

About midnight, North Vietnamese regulars attacked, and the then Lieutenant Fischer was hit by shrapnel from a rocket. It tore a piece out of his shoulder, but his newly-issued flak jacket saved his life when other shrapnel hit him in the chest. He floated on Cloud Nine, pumped with morphine, until he was evacuated by helicopter next morning.

Today Mr Fischer will address "The Great Debate - Conscription and National Service 1912-1972", a conference in Melbourne hosted by Military History and Heritage Victoria.

He will argue that the selective conscription that sent young men to Vietnam should never be repeated. If circumstances ever again required conscription, he believes, it must be "all in or none in", and it should include both men and women.

He says he once believed that "the same number of balls or marbles marked with a particular date for the six monthly ballots were placed in the barrel for each day of the relevant six month period."

"I no longer think this is the case, at least not the exact true random outcome," says Fischer.

"It appears that after the Department of Labour and National Service and the Army reviewed the trades and experience and education of each registrant, the number of days to be drawn was decided but not all were then called up for the actual dates drawn."

Six months ago, he asked Attorney-General George Brandis to investigate a simple question: Was the National Service ballot stacked in favour of certain pre-determined dates [and] were all fit enough taken for each birthdate drawn?

It was a reasonable question. The majority of ballots were conducted in secret, and it wasn't until 1970 that the process was turned into a public hoopla for TV.

The answer came back from National Archives, giving all birthdates drawn from 1965 until the Whitlam Government ended conscription in 1972.

Fischer discovered that 13 marbles had been drawn for his month of May (he was born in 1946), but only four had appeared in February in that same year.

"This is almost beyond random possibilities," he declares.

More to the point, it became clear large numbers of young men whose birthdays had been drawn from the lottery were not called up at all, even allowing for those exempted because they were deemed unfit, received deferment because they were at university, were members of the clergy, joined the Citizens Military Forces instead or were judged to have a conscientious objection.

Of the 804,286 twenty-year-olds registered for national service between 1964 and 1972, only 63,735 ended up in the Army.

"It seems the National Service Ballot was not formally stacked," concludes Fischer, "But it may have been stacked on the margins as - in short - not all were taken that had registered for a particular birth date drawn out in the twice yearly ballot," says Fischer.

"... It appears some person within the system played God big time."

If Tim Fischer, former deputy prime minister, is right, none of us should have bothered registering. It was a government-run scam that ruined a lot of lives.