The eight-week trial offered a gripping account of Manning’s transformation from a shy soldier who deployed to Baghdad as an intelligence analyst in 2009 to a mole for the anti-secrecy group WikiLeaks, which disclosed more than 700,000 documents Manning gathered.

Had Manning been convicted of aiding the enemy, Manning would have faced a life sentence in prison without the possibility of parole. Civil libertarians saw the prospect of a conviction on that charge, which has not been used since the Civil War, as a dangerous precedent that could have would have sent an unmistakable message to would-be government whistle-blowers.

“The heart of this matter is the level of culpability,” said retired Air Force Col. Morris Davis, a former chief prosecutor at the U.S. military prison in Guantanamo Bay, Cuba. He noted that Manning has already pled guilty to some charges and admitted leaking secret documents that he felt exposed wartime misdeeds. “Beyond that is government overreach.”

If found guilty of all charges, including aiding the enemy, Manning would face a sentence of life in prison without the possibility of parole.

The planned announcement of the verdict follows an eight-week trial at Fort Meade in Maryland, where military prosecutors argued that Manning, 25, betrayed his oath and his country, and assisted al-Qaeda because the terrorist group was able to access secret material once WikiLeaks posted it.

Hours before the verdict, about two dozen Manning supporters demonstrated outside Fort Meade wearing “truth” T-shirts and waving signs proclaiming their admiration for the former intelligence analyst, the Associated Press reported.

“He wasn’t trying to aid the enemy,” said Barbara Bridges, 43, of Baltimore. “He was trying to give people the information they need so they can hold their government accountable.”

As dozens of journalists were admitted to the installation amid tight security, dogs trained to sniff out explosives searched their vehicles before they were escorted to a media room where the court proceedings were to be broadcast live on a screen.

The government’s pursuit of the charge of aiding the enemy under a theory that had not been used since the Civil War troubled civil libertarians and press-freedom advocates. They said the publication of secret defense information online could expose any leaker to life in prison and will chill press scrutiny of the military.

The government relied on a case from the Civil War to bring the charge: In that trial, a Union Army private, Henry Vanderwater, was found guilty of aiding the enemy when he leaked a Union roster to an Alexandria newspaper. Vanderwater received a sentence of three months hard labor and was dishonorably discharged.

The sentencing phase of the trial at Fort Meade outside Baltimore would begin Wednesday, if Manning is convicted. If there is a conviction, the prosecution is expected to press the judge, Col. Denise Lind, to impose the maximum sentence. The government would present in a closed session of the court the classified damage assessments conducted by government agencies after the disclosures by WikiLeaks.

Defense attorney David Coombs would also be able to offer mitigating evidence about Manning’s motives and his state of mind when he turned the material over to the group.

Manning would be likely to serve any sentence at the U.S. Disciplinary Barracks at Fort Leavenworth, Kan.

Manning, of Crescent, Okla., enlisted in the Army in October 2007, hoping to fund his college education through the G.I. Bill. He trained as an all-source intelligence analyst at Fort Huachuca, Ariz., and was stationed at Fort Drum, N.Y.

The military said Manning’s service was troubled from the start. He took more time than usual to pass basic training and struggled to connect with fellow soldiers. In October 2009, Manning’s unit was deployed to Iraq, where as part of his assignment he was able to access classified networks containing military and diplomatic documents.

In closing arguments last week, Maj. Ashden Fein, a military prosecutor, said Manning had disregarded the “sensitivity” of the material he leaked and “decided to release it to a bunch of anti-government activists and anarchists to achieve maximum exposure, the maximum exposure, and advance his personal quest for notoriety.”

Coombs has argued that Manning grew increasingly disturbed by the violence in Iraq and that his objective in copying secret documents while at a forward operating base there and leaking them to WikiLeaks was to “spark a worldwide discussion.” During the past two years of proceedings, Coombs has portrayed Manning as both naive and “well-intentioned.”

On Feb. 3, 2010, Manning turned over a trove of documents that became known as the War Logs to WikiLeaks. He attached a note: “This is possibly one of the more significant documents of our time, removing the fog of war, and revealing the true nature of the 21st century asymmetric warfare. Have a good day.”

After that transmission, Manning developed a more robust relationship with WikiLeaks, passing on more than 700,000 documents and other material to the Web site, including video of an Apache helicopter engaging what the pilots believed were armed fighters in Baghdad. WikiLeaks called it “Collateral Murder.” Eleven people were killed in the incident, including an unarmed Reuters news agency photographer and his driver.

Manning developed an online relationship with a person believed to be Julian Assange, one of the founders of WikiLeaks.

“We conversed on a near daily basis, and I felt we were developing a friendship,” said Manning in a statement in March. “The conversations covered many topics and I enjoyed the ability to talk about pretty much anything, and not just the publications that the WLO (WikiLeaks) was working on.”

Manning was arrested in Iraq in May 2010 and transferred to the brig at Marine Corps Base Quantico in July 2010. He was kept alone in a windowless six-by-eight-foot cell 23 hours a day and forced while on suicide watch to sleep in a “suicide smock.”

In March 2011, after eight months of confinement, Manning quipped sarcastically that he could kill himself with the elastic of his underwear if he wanted to.

Lind ruled in January that any sentence the Army private receives should be reduced by 112 days because of his mistreatment in confinement.