After almost 6000 submissions and hundreds of testimonies, the final report by the Royal Commission into Defence and Veteran Suicide will be handed down on Monday.
Julie-Ann Finney lost her 38-year-old son David Finney, after the navy veteran died by suicide in 2019.
She led a campaign of grieving mothers who successfully petitioned the former Morrison federal government for the inquiry.
Speaking ahead of the report's release, chair Nick Kaldas said it was difficult to judge whether defence leadership had turned a corner in confronting problems within the organisation three years on.
"My fear is that the royal commission will come and go, and there may be people who feel that they can continue doing what they want to do, which is wrong," he told AAP.
"Therefore it's up to the Australian Defence Force, and in particular the leadership, to actually commit to changing the culture."
Praising the "exceptional" bravery and courage of everyone who came forward, Mr Kaldas said the evidence heard had affected him and fellow commissioners James Douglas KC and Dr Peggy Brown.
"It has touched all of us and will remain with us, probably for life," he said.
Amongst the hundreds of witnesses to give evidence, was defence force chief Admiral David Johnston who told one of the hearings he wasn't able to achieve all the reforms to the military justice system he wanted, and rejected accusations it had been weaponised.
Mr Kaldas said the issue of sexual abuse and other forms of misconduct within the defence force hadn't received the attention it deserved.
But the chair was "heartened" by Admiral Johnston's "blunt" statements and looked to his leadership to fix the problems aired during the inquiry.
"One of the main lessons is that the vast majority of those who have suicided ... have never been to war," Mr Kaldas said.
Families brought pictures of their loved ones to an August ceremony to formally close the inquiry. (Bianca De Marchi/AAP PHOTOS)
"It's what's happening in the barracks, it's how they're being treated by their chain of command and their workplace. It's unacceptable behaviour going unchecked."
He said the deteriorating geopolitical environment meant the nation had to ensure its military remained an attractive employer of choice to potential recruits.
A key recommendation in the report will call for a body to be set up after the royal commission to monitor the situation and report publicly.
"If any government rejects our recommendation to establish that entity, which is essentially to recreate the interim national commissioner for suicides, we're actually going to leave the constituency in a worse place than when we found them," the chair said.
As the inquiry wraps up, Mr Kaldas wants the royal commission to become a "line in the sand" and save countless further people from trauma.
"I hope and pray that the government of the day and the bureaucrats actually embrace the problems and deal with it once and for all," he said.
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