Daniel Ellsberg has passed away, his family announced in a statement on Friday. Ellsberg was the whistleblower who revealed the American government’s lies about the Vietnam War by leaking the Pentagon Papers to some of the largest newspapers in the country.

He was 92.

Ellsberg passed away around four months after tweeting that he had been given the diagnosis of “inoperable pancreatic cancer.”

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When the U.S. government understood the Vietnam War could not be won early on, according to a 7,000-page study secretly ordered by the Defence Department in 1969, Ellsberg and a colleague called Anthony Russo were working as analysts for the RAND Corporation.

Before deciding to leak the study to the media, Ellsberg and Russo had provided the data to a number of members of Congress and other officials.

When the Pentagon Papers were initially published in The New York Times and then The Washington Post, then-President Richard Nixon called them traitors and attempted to halt their release. However, the U.S. Supreme Court sided with the newspapers in a historic decision in June 1971 that forbade prior limitation of free expression.

Ellsberg turned himself in to the Boston office of the U.S. Attorney two days prior to that historic ruling.

He said, “I felt that as an American, as a responsible citizen, I could no longer cooperate in keeping this information from the American public. I made this decision knowingly at my own risk, and I’m ready to face all the repercussions of it.”

Following the leak, Ellsberg and Russo were accused of espionage, theft, and conspiracy. Ellsberg was put on trial in Los Angeles, where the papers had been duplicated, and if found guilty, he might spend up to 115 years in jail.

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However, a federal judge dismissed the case in 1973 after finding that the government had engaged in improper behavior, including an attempt by the White House to undermine Ellsberg by breaking into his Beverly Hills psychiatrist’s office.

When Ellsberg returned to RAND in 1967 after serving for two years as a State Department employee stationed in Vietnam, he started making contributions to a top-secret history of the conflict that McNamara had commissioned.

It was completed in 1968 and thereafter known as The Pentagon Papers.

By that time, Ellsberg had already begun to lose interest in a conflict he had previously championed.

Ellsberg was branded “The Most Dangerous Man in America” when his involvement in publishing The Pentagon Papers was made public.