It's the biggest intelligence breach in U.S. history -- the leaking of more than a half million classified documents on the WikiLeaks website throughout 2010. At the center of the controversy stands Bradley E. Manning, the Army intelligence analyst who's charged with handing them over.

Who is Bradley Manning, and what does his story tell us about how and why the secret cache of documents may have been leaked? In "WikiSecrets," FRONTLINE correspondent Martin Smith gained exclusive access to those closest to Manning -- including his father, close friends and his Army bunkmate -- and uncovers video of Manning taken around the time of the alleged handover of classified information.

Have a question about last night's show? Join us for a live chat at 1 p.m. EST. "WikiSecrets" producers Martin Smith and Marcela Gaviria will be on hand.

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