. >> reporter: she sought solace online in wikileaks-themed chat rooms. >> memes of being able to safely and securely reveal government wrongdoing. >> you decide to risk your career, to break the law. what was it that you were seeing that compelled you to do that? >> i stopped seeing just statistics and information. and i started seeing people. >> currently engaging approximately eight individuals -- >> reporter: so manning decided to leak and release that air strike video. and later other classified documents. to wikileaks. >> the material is dramatic. it was classified. >> reporter: thus began a game of cat and mouse with a contact named nathaniel who manning said she believed was julian assange himself. at the time wikileaks was just an obscure open government website. why wikileaks, then? >> i think it's important to remember the context. i tried to go to "the washington post" first. i tried to go to the "new york times." >> reporter: over the course of four months, she leaked diplomatic cables, battlefield reports, and guantanamo detainee profiles. more than 700,000 documents in all

. >> reporter: she sought solace online in wikileaks-themed chat rooms. >> memes of being able to safelyped seeing just statistics and information. and i started seeing people. >> currently engaging approximately eight individuals -- >> reporter: so manning decided to leak and release that air strike video. and later other classified documents. to wikileaks. >> the material is dramatic. it was classified. >> reporter: thus began a game of cat and mouse with a contact named nathaniel who manning said she believed was julian assange himself. at the time wikileaks was just an obscure open government website. why wikileaks, then? >> i think it's important to remember the context. i tried to go to "the washington post" first. i tried to go to the "new york times." >> reporter: over the course of four months, she leaked diplomatic cables, battlefield reports, and guantanamo detainee profiles. more than 700,000 documents in all. the impact, explosive. >> it's the biggest leak in u.s. military history. >> there are names. there are operations. >> it is an attack on the international community. >