David McBride, who helped expose allegations of war crimes committed by Australian soldiers, did so because he believed lower-level troops were being used as scapegoats by leaders.
McBride pleaded guilty this month to three charges of stealing classified information and passing it on to journalists without permission.
He will be sentenced in the ACT Supreme Court on March 12.
The prosecution sought to push the case the former military lawyer had not leaked the confidential documents to expose war crimes but because he wanted to make a point about the over-investigation of some soldiers.
In a sealed affidavit from 2021 that was never tendered to court, McBride said there was a disparity in war crime investigations between soldiers and their superiors.
He said reports of a February 2009 incident "greatly affected" him when he was in Afghanistan in 2011, adding he became suspicious of official reports and began making enquiries.
The whistleblower recalled how two special forces soldiers killed five children in a raid in the Uruzgan province and the inquiry officer recommended an investigation into potential war crimes.
Charges were brought against the two soldiers and a case was prepared against their commander, McBride said.
The soldiers had acted on intelligence about where a known Taliban member was living, but after they couldn't locate him moved to a different house for which they had no reason to approach, he said.
There they blew open the doors and were met by a man returning fire "defending himself", McBride alleged.
"Under the rules of engagement, they should have assessed the threat and considered that he was a sole shooter and that he was trapped," he wrote.
But the soldiers kept firing, he said, and threw a grenade into the bedroom.
"After the first grenade, the soldiers heard screaming children. Despite hearing the crying of the children, they decided to throw a further grenade," he wrote.
"After this, there was silence. The whole situation sickened me."
McBride said the inquiry officer found the actions justified manslaughter or murder charges and warranted a trial.
But the charges were thrown out at a pre-trial hearing by the chief military judge "on the grounds that Australian soldiers did not owe any duty of care to Afghan civilians".
"I believe this was a perverse judgment that made a mockery of the rules of engagement," he said.
Extensive media coverage highlighted "a system that selectively prosecuted some and encouraged a culture of impunity amongst others in Afghanistan", he said.
McBride pointed to the story of soldiers killing an unseen sleeping child hitting the media "at lightning speed", despite it being an accident in his view as the bullet went through an armed individual who posed a threat.
"The apparent execution of civilians and prisoners was being ignored while innocent soldiers were being prosecuted at the whim of either media or political imperative," he wrote.
"In short, they were rewarding criminals and punishing and tormenting good soldiers where there were no prospects of convictions. I was suspicious that the latter were being used as a smoke screen to cover the former."
McBride said he was pressured to drop his proposed complaint on a number of occasions and was on "high alert to the dangers" facing his career and his life.
He said it was a burden for him to reveal the information as he didn't want to be seen as "un-Australian, or anti-soldier, or overly sensitive about civilian and prisoner deaths".
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