Former prime minister John Howard has led an unlikely political union in a chorus against selling inner-city military grounds he described as "the soul of a nation".
About a thousand gathered in Moore Park opposite Sydney's Victoria Barracks on Sunday to rally against the proposed sale of the military site, which was established in the 1840s.
The 13-hectare barracks is one of more than 60 sites put forward by the Defence Department for divestment in a drive to make multibillion dollar savings on its nationwide estate.
The plan to axe Victoria Barracks for military use has united the coalition, Greens and One Nation in opposition, while key independents and the RSL are also against the move.
"We think it is a precious, irreplaceable, not-for-sale national asset," Mr Howard told the rally to cheers.
"I am all in favour of government spending less and taxing less ... but what is more important to the soul of a nation, its history, its heritage and all its gone before it?"
Defence Minister Richard Marles is backing the plans, arguing defence must be equipped for modern challenges.
"It is not my priority for defence to be a heritage organisation (or) see defence manage the oldest wine cellar in Australia," he said in September.
Mr Marles pinned opposition to the sale on "a few former generals who liked hanging out there", but a range of Labor's political opponents attended the rally to support its goals.
Federal opposition leader Angus Taylor, Greens leader David Shoebridge and Wentworth MP Allegra Spender were among the speakers, as were former Liberal prime minister Tony Abbott and state opposition leader Kellie Sloane.
"Isn't it wonderful to be at this protest where the only flag on display is the Australian flag and not the Palestinian one," Mr Abbott said.
Mr Shoebridge was jeered for mentioning the Aboriginal history of the site and also for arguing cancelling the AUKUS defence pact would produce better savings, but he won support for an anti-privatisation message.
"No more privatisation, no more selling of the public estate, it stays in public hands," he said.
Each of the Liberal speakers tied the fate of the barracks to Prime Minister Anthony Albanese.
"Albo, do not sell off our barracks," Ms Sloane said.
"If you sell it, you are erasing history and you are taking a piece of our hearts."
Ms Sloane pledged to put forward a state law to prevent the sale of the barracks if the coalition triumphs at March's state election.
Labor premier Chris Minns has also spoken in favour of the barracks remaining in public hands, backing a heritage listing that would prevent development of the site.
An online petition championed by the federal opposition has gathered more than 119,000 signatures of support for retaining the barracks in its current state.
