A petition to upgrade the medal of Gomeroi war hero Private William Allan Irwin has been launched in a renewed push to secure long-overdue recognition for his extraordinary bravery during World War I — a story his family says has gone largely unrecognised for more than a century.

Joining forces with Yuwaalaraay documentary filmmaker Dylan Nicholls, Private Irwin's family is petitioning for his Distinguished Conduct Medal to be upgraded to the Victoria Cross — Australia's highest military honour for gallantry.

During intense fighting near Mont St Quentin in France in August 1918, Private Irwin captured three enemy machine-gun posts and their crews under relentless machine-gun fire— actions that would earn him the posthumous Distinguished Conduct Medal.

But for his family and supporters, that honour falls short of recognising what they describe as one of the most courageous acts by an Australian soldier in World War I.

"There are a lot of white Australians who do not know what this man's done either. You know, he's been hidden for a long time," Peter Milliken, a proud Gomeroi man and Private Irwin's great-nephew, told National Indigenous Times.

"Half of Australia, or three-quarters of Australia, wouldn't have even heard of the man...bringing him to the light, it's a good thing for the country as well, because I think they need to be told the truth about this country."

The petition follows years of unsuccessful appeals through official channels, with Mr Milliken hoping public support may finally prompt a formal review of Private Irwin's medal.

"Look, I've sent three letters to the Governor General. I've sent it to a number of other MPs, including Richard Marles," he said. "They've all referred me back to the DHA, which I always get the same response, they won't do this."

With over 2000 signatures and growing, the petition is urging action from Defence Minister Richard Marles, the Governor-General, and the Defence Honours and Awards Appeals Tribunal.

"Hopefully, it'll give great support," said Mr Milliken. "This bloke's a real hero, so sign up, and I think that'll bring attention. There are 10,000 signatures on whether the government have to look into it."

National Indigenous Times also spoke with Mr Nicholls, the filmmaker behind the documentaries Bringing His Spirit Home and Yaluu: See You Again, which explore Private Irwin's story and the broader fight for recognition of Aboriginal soldiers.

Mr Nicholls said he "just couldn't understand" why Private Irwin was not decorated with the highest military honour — the Victoria Cross.

"If you look at the eligibility criteria for Victoria Cross, it's all about bravery, gallantry, self-sacrifice," he explained.

"And if you read about what William did, it's just the definition of Victoria Cross. It's one of the bravest things you could think of that a soldier could do.

"It's a difficult question to answer. I don't know whether it was due to race, but you sort of have to wonder, what was it due to? Because this person deserved it, this soldier deserved his Victoria Cross.

"I know that on the battlefield, all the stories are that Indigenous people were equal to anyone else. That they didn't see the colour of skin, the only colour that mattered was green, the colour of their uniform...There was no racial discrimination there."

But Mr Nicholls says the decision to award a Distinguished Conduct Medal instead of a Victoria Cross continues to raise questions about the criteria for recipients.

"But you do have to wonder, like you know, who is responsible for nominating a VC, who is responsible for awarding. That goes up the decision channel and, as it gets higher and higher, you have to wonder whether there was discrimination," he said.

But while a formal review may answer those questions, Mr Nicholls says upgrading the medal remains the priority.

"I just think what Australia should do is give him what he deserves, like this is what he deserves. He should be recognised," he said.

"I think it would be such an incredible thing for this country to award an Indigenous Australian with the highest military honour, to recognise his contribution and also just acknowledge that we were a part of these wars as well.

"It wasn't just non-Indigenous men that served, there are Indigenous soldiers like William that did some really brave acts that really should have been awarded the Victoria Cross."

To support the petition, visit online.

Yaluu: See You Again will premiere at 6:30 PM on Sunday, April 26, on ABC Compass.