The lead prosecutor, Maj. Ashden Fein, said Manning knew the material would be seen by al-Qaida, a key point prosecutor needed to prove to get an aiding the enemy conviction. Even Osama bin Laden had some of the digital files at his compound when he was killed.
Some of Manning's supporters attended nearly every day of two-month trial, many of them protesting outside the Fort Meade gates each day before the court-martial. They wore T-shirts with the word "truth" on them, blogged, tweeted and raised money for Manning's defense. One supporter was banned from the trial because the judge said he made online threats.
Hours before the verdict, about two dozen demonstrators gathered outside the gates of the military post, proclaiming their admiration for Manning.
"He wasn't trying to aid the enemy. He was trying to give people the information they need so they can hold their government accountable," said Barbara Bridges, of Baltimore.
The court-martial unfolded as another low-level intelligence worker, Edward Snowden, revealed U.S. secrets about surveillance programs. Snowden, a civilian employee, told The Guardian his motives were similar to Manning's, but he said his leaks were more selective.
Manning's supporters believed a conviction for aiding the enemy would have a chilling effect on leakers who want to expose wrongdoing by giving information to websites and the media.
Before Snowden, Manning's case was the most high-profile espionage prosecution for the Obama administration, which has been criticized for its crackdown on leakers.
The WikiLeaks case is by far the most voluminous release of classified material in U.S. history. Manning's supporters included Pentagon Papers leaker Daniel Ellsberg, who in the early 1970s spilled a secret Defense Department history of U.S. involvement in Vietnam.
The 7,000 pages of the Pentagon Papers showed that the U.S. government repeatedly misled the public about the Vietnam War.
The material WikiLeaks began publishing in 2010 documented complaints of abuses against Iraqi detainees, a U.S. tally of civilian deaths in Iraq, and America's weak support for the government of Tunisia — a disclosure that Manning supporters said helped trigger the Middle Eastern pro-democracy uprisings known as the Arab Spring.
The Obama administration said the release threatened to expose valuable military and diplomatic sources and strained America's relations with other governments.
Prosecutors said during the trial Manning relied on WikiLeaks and its founder Julian Assange for guidance on what secrets to "harvest" for the organization, starting within weeks of his arrival in Iraq in late 2009.
Federal authorities are looking into whether Assange can be prosecuted. He has been holed up in the Ecuadorean Embassy in London to avoid extradition to Sweden on sex-crimes allegations.
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