In 2013, Manning was convicted of violating the Espionage Act and sentenced to 35 years in Fort Leavenworth prison. The data she leaked included 250,000 diplomatic cables, evidence that civilian deaths in the Iraq war were likely much higher than public estimates, and demonstrations of American military partners abusing detainees.
Manning is a transgender woman who was known as Bradley when she was an active army analyst. Activists and Manning's lawyers have been calling for her to be pardoned, arguing she is in danger at Fort Leavenworth, a male military prison. She attempted to commit suicide twice last year.
Manning is irrevocably tied to Wikileaks and Assange, the organization's founder who also faces espionage charges in the US for publishing the information that Manning provided. Assange is currently hiding out at London's Ecuadorian embassy, which has granted him asylum as he flees authorities in multiple countries: On top of his charges in the US related to Wikileaks, he's wanted in Sweden to answer allegations of rape and sexual assault.
In September, Assange said that he would turn himself in to the US if Manning was granted clemency or the charges against her were dropped. Additionally, just five days ago, the Wikileaks Twitter account said, "If Obama grants Manning clemency Assange will agree to US extradition despite clear unconstitutionality of DoJ case."
There's no word yet on Assange's plans now that Manning's sentence has been mostly wiped away. The decision to commute Manning's sentence came as a surprise, though earlier this month the Obama administration laid the groundwork for her possible clemency by contrasting her position with NSA whistleblower Edward Snowden's.
"Chelsea Manning is somebody who went through the military criminal justice process, was exposed to due process, was found guilty, was sentenced for her crimes, and she acknowledged wrongdoing," White House press secretary Josh Earnest said on January 13th. "Mr. Snowden fled into the arms of an adversary, and has sought refuge in a country that most recently made a concerted effort to undermine confidence in our democracy. ...Obviously, as Chelsea Manning has acknowledged, and as we have said many times, that the release of the information that she provided to WikiLeaks was damaging to national security. But the disclosures by Edward Snowden were far more serious and far more dangerous."
Obama has now commuted the sentences of more people than any other President in US history, with a total of 1,385 individuals.