Chelsea Manning on Sunday told a crowd at the annual New Yorker Festival in New York that the information she leaked did not expose names of informants.
“These aren’t intelligence documents,” she said. “It’s historical data.”
She went on, "There's nothing sensitive in there, there's no troop movements," she added. "It was a historical record of everything that had happened in Iraq and Afghanistan."
Manning, who was released in May after seven years in military prison, was by turns impassioned, defensive, humorous and occasionally tearful in a panel discussion with New Yorker writer Larissa MacFarquhar.
She became emotional when asked what she thought the best result had been from her leaking of hundreds of thousands of classified documents to WikiLeaks. "Look, I haven't had time to deal with these questions," she said. "All I've been doing is fighting for my life for the last seven years."
The 29-year-old transgender woman was known as Bradley Manning when she was convicted and sentenced to 35 years in prison. In his last days in office, President Barack Obama commuted the rest of her sentence.
Manning has made only a few appearances since her release. Last month, Harvard University reversed a decision to name her a visiting fellow after CIA director Mike Pompeo scrapped a planned appearance over the designation, calling Manning an "American traitor."
And Manning tweeted two weeks later that she'd been denied entry into Canada because of her U.S. criminal record.
While some see her as a traitor, others see her as a hero for exposing truths of war. One audience questioner cried as she mentioned the ordeal Manning had been through.
At times, Manning told MacFarquhar she was legally unable to get into certain details. And when asked how she would advise other aspiring leakers to proceed, she said simply that everyone needed to make their own decisions.
Manning spoke of her childhood in small-town Oklahoma -- "a typical generic town in the middle of the country" -- her turbulent family life, and a short time living homeless on the streets of Chicago.
She said she'd learned to program computers by age 8 or 9, and eventually joined the military because she thought "I could use my skills and make a difference." Once she got to Iraq, she said, she was overwhelmed by the death and destruction she saw.
On a 10-day leave back home in Washington, she said, she first tried to leak the documents to the Washington Post or The New York Times -- simply because she had seen the movie "All the President's Men." Unwilling to trust email, she called the newspapers from public phones at various Starbucks locations.
But the newspapers were unable to establish encrypted communications channels, so she went to WikiLeaks, because, she said, "I was running out of time."
Manning spoke in detail of her time in prison, especially in solitary confinement. "Humans are a social creature," she said, fighting tears. "We need connections. We need to be with each other."
She said she got through much of the seven years by setting small, incremental goals, like getting "from breakfast to lunch to dinner to sleep." When the rules forbid her to exercise, she said, she started to dance, and her guards didn't stop her. So she thought, she said, "OK, that's how I'll exercise, like Zumba."
Manning has now become an activist -- for LGBT rights, for transparency in government, and also against what she called an alarming level of surveillance in society. "I feel like prison has encroached into the outside world," she said. "You've got militarized forces walking around on American streets. It's quite frightening."
She also had a message for engineers and software designers: Pay attention to the potential uses of what you're designing, because it can be used for different purposes than intended.
Manning was asked by one tearful audience questioner whether her experience had made her "more cynical about fairness."
"I do have cynical moments," she said, tearing up again. "But then I get past them, you know? I turn to my friends, and I turn to my family ... and then they cheer me up."
The Associated Press contributed to this report