He was found guilty of most of the remaining charges against him, with the judge accepting some of the guilty pleas he made previously to lesser charges.
If he had been found guilty on the aiding the enemy charge, Manning could have been sentenced to life in prison. He could be sentenced to up to 20 years behind bars on some of the other charges.
Manning already has spent three years in custody.
Whether Manning is a whistle-blower or a traitor to his country has been hotly debated.
Authorities have accused him of delivering three quarters of a million pages of classified documents and videos to the secret-sharing site WikiLeaks, which has never confirmed the soldier was the source of its information. The material covered numerous aspects of U.S. military strategy in Iraq, gave what some called a ground view of events in the Afghanistan war and revealed the inner workings of U.S. State Department diplomacy in leaked cables.
When he entered his guilty pleas on the lesser charges this year, Manning spent more than an hour in court reading a statement about why he leaked the information.
He said the information he passed on "upset" or "disturbed" him, but there was nothing he thought would harm the United States if it became public. Manning said he thought the documents were old and the situations they referred to had changed or ended.
"I believed if the public was aware of the data, it would start a public debate of the wars," he said during his court-martial. He was "depressed about the situation there," meaning Iraq, where he was stationed as an intelligence analyst.
The young soldier from a small town in Oklahoma said that he first tried to give the information to The Washington Post, but a reporter there didn't seem like she took him seriously.
He left a voice mail for The New York Times and sent an e-mail to the newspaper but, he says, he didn't hear back.
So, he said, he decided to give the information to WikiLeaks.
At some point, according to a California hacker Adrian Lamo, who says he communicated via instant messaging with Manning, the soldier confessed to possessing sensitive documents.
Shortly after alleged texts between Manning and Lamo were published in 2010, Lamo spoke to CNN.
He said he turned Manning in to authorities. His reason?
"... it seemed incomprehensible that someone could leak that massive amount of data and not have it endanger human life," Lamo said. "If I had acted for my own comfort and convenience and sat on my hands with that information, and I had endangered national security ... I would have been the worst kind of coward."
As Manning's court case dragged on, in December 2011 his defense argued that the military didn't heed warning signs that the soldier was falling apart mentally.
A few months before Manning was arrested, Army command referred him to a psychologist for evaluation because he appeared to be "under considerable stress" and "did not appear to have any social support system and seemed hypersensitive to any criticism" and "was potentially a danger to himself and others."