Forty-four years ago today the American public finally began to read some truth about their country's involvement in the political struggle of Vietnam from 1945 through mid-1968. It wasn't pretty. In fact the outrage it, the Kent State murders the year before, and the Watergate scandal in June of 1972 would heighten revolutionary fervor from coast to coast and consume Nixon's presidency in 1974.
Here is a fine summary of the Pentagon Papers story from history.com:
The New York Times begins to publish sections of the so-called “Pentagon Papers,” a top-secret Department of Defense study of America’s involvement in the Vietnam War. The papers indicated that the American government had been lying to the people for years about the Vietnam War and the papers seriously damaged the credibility of America’s Cold War foreign policy.
In 1967, Secretary of Defense Robert McNamara ordered his department to prepare an in-depth history of American involvement in the Vietnam War. McNamara had already begun to harbor serious doubts about U.S. policy in Vietnam, and the study–which came to be known as the “Pentagon Papers”–substantiated his misgivings. Top-secret memorandums, reports, and papers indicated that the U.S. government had systematically lied to the American people, deceiving them about American goals and progress in the war in Vietnam. The devastating multi-volume study remained locked away in a Pentagon safe for years. In 1971, Daniel Ellsberg, a Defense Department employee who had turned completely against the war, began to smuggle portions of the papers out of the Pentagon. These papers made their way to the New York Times, and on June 13, 1971, the American public read them in stunned amazement. The publication of the papers added further fuel to the already powerful antiwar movement and drove the administration of President Richard Nixon into a frenzy of paranoia about information “leaks.” Nixon attempted to stop further publication of the papers, but the Supreme Court refused to issue an injunction.
The “Pentagon Papers” further eroded the American public’s confidence in their nation’s Cold War foreign policy. The brutal, costly, and seemingly endless Vietnam War had already damaged the government’s credibility, and the publication of the “Pentagon Papers” showed people the true extent to which the government had manipulated and lied to them. Some of the most dramatic examples were documents indicating that the Kennedy administration had openly encouraged and participated in the overthrow of South Vietnamese President Ngo Dinh Diem in 1963; that the CIA believed that the “domino theory” did not actually apply to Asia; and that the heavy American bombing of North Vietnam, contrary to U.S. government pronouncements about its success, was having absolutely no impact on the communists’ will to continue the fight.
There is more at the site here.