Daniel Ellsberg, the whistleblower who leaked the 'Pentagon Papers' died after a battle with terminal pancreatic cancer.
Mr Ellsberg died on Friday, Jue 16, at his home in Kensington, California, at the age of 92.
He had announced the diagnosis in an email to friends and supporters on March 1, saying he had declined chemotherapy and would spend whatever time had left giving talks and interviews about the Russian invasion of Ukraine, the perils of nuclear war and the importance of First Amendment protections.
In 1971 the military analyst disclosed top secret information about the Vietnam War, exposing years of US government lies. The groundbreaking disclosure led to a landmark Supreme Court ruling on press freedoms, enraging the Nixon administration.
It served as the catalyst for a series of White House-directed 'dirty tricks' in an attempt to discredit Mr Ellsberg which went on to snowball into the Watergate scandal, which ended up with President Richard Nixon resigning. Mr Ellsberg was dubbed "the most dangerous man in America" following the Pentagon Papers leak.
The Pentagon Papers included around 7,000 pages of revelations about deceptions by successive presidents who had bypassed Congress, exceeded their authority and misled American citizens.
Mr Ellsberg was working as an analyst for the RAND Corporation in 1969 when he and colleague Anthony Russo secretly photocopied a 7,000-page study. The study had been commissioned by the Defense Department and revealed the US government knew early on the Vietnam War could not be won.
Mr Ellsberg and Mr Russo initially offered the study to several members of Congress and other government officials before deciding to leak it to the press.
The pair were branded as traitors by then-President Nixon who tried to put a stop to the publication of the papers - first in the New York Times and then in the Washington Post.
Mr Ellsberg surrendered himself to the US Attorney's office in Boston two days before the Supreme Court sided with the newspapers in barring prior restraint of free expression.
"I felt that as an American citizen, as a responsible citizen, I could no longer cooperate in concealing this information from the American public," he said.
"I did this clearly at my own jeopardy and I am prepared to answer to all the consequences of this decision."
Mr Ellsberg was charged with espionage, conspiracy and other crimes in relation to the leak. He was tried in a federal court in Los Angeles, but on the eve of jury deliberations, the judge decided to throw out the case.
The judge cited government misconduct, including illegal wiretapping, a break-in at the office of Mr Ellsberg's former psychiatrist and even a bribery offer from President Nixon to appoint the judge as director of the Federal Bureau of Investigation.
Mr Ellsberg was born in Chicago in 1931, before being raised in Detroit. He was the son of non-religious Jews who became devout Christian Scientists.
His first encounter with tragedy came in 1946, when his mother and sister died in a car crash after his father fell asleep at the wheel. He had also been in the car at the time.
In 1952, Mr Ellsberg earned his economics degree from Harvard, before enlisting in the Marines two years later. He returned to Harvard in 1957 after being discharged as a first lieutenant.
He worked a first stint at RAND and earned a Ph.D in economics from Harvard before going to work at the Pentagon in 1964 under then-Defense Secretary Robert McNamara.
He spent two years stationed in Vietnam, working for the State Department, before returning to RAND in 1967. There he began contributing to a top-secret history of the war which had been commissioned by Mr McNamara.
During his time in Vietnam, he saw the true extent of the war there. "I saw it was all very hard on those people," he told columnist Mary McGrory.
"But I told myself that living under Communism would be harder, and World War III, which I thought we were preventing, would be worse."
Mr Ellsberg's contribution to Mr McNamara's study was on the more modest side - but he was disturbed at the sweeping conclusions being made. Successive presidents had widened the war while concealing the facts from Congress and the American people.
While back at RAND he began attending antiwar conferences. He began to openly oppose the war, writing letters to newspapers, composing articles and testifying at the trials of draft resisters.
Even after Mr Nixon resigned, Mr Ellsberg continued to be active in the antiwar movement. He spoke at rallies and campuses across the country, advocated disarmament and spoke against nuclear weapons.
He is survived by his wife, children, five grandchildren and one great-grandaughter.
