In one of his final acts before leaving office, President Barack Obama on Tuesday commuted the prison sentence of Chelsea Manning, the former U.S. military intelligence analyst behind the biggest breach of classified materials in U.S. history, the White House said. Manning has been a focus of a worldwide debate on government secrecy since she provided more than 700,000 documents, videos, diplomatic cables and battlefield accounts to the anti-secrecy group WikiLeaks - a leak for which she was sentenced to serve 35 years in prison. Manning, formerly known as U.S. Army Private First Class Bradley Manning, was born male but revealed after being convicted of espionage that she identifies as a woman. Manning, who is held at the Fort Leavenworth, Kansas, military prison, accepted responsibility for…