The Defense Department's own secret history proved that four presidents had lied to the public about Vietnam — and the government went to court to stop Americans from reading it.
In June 1967, Defense Secretary Robert McNamara — increasingly private doubts about a war he had helped build — commissioned a classified internal history of U.S. involvement in Vietnam. The result was 7,000 pages across 47 volumes, covering American policy from the Truman administration through 1968. It was marked 'Top Secret — Sensitive' and shared with almost no one. McNamara himself later said he never read it.
The study's conclusions were damning. It showed that four consecutive administrations — Truman, Eisenhower, Kennedy, and Johnson — had systematically deceived Congress and the public about the nature, scope, and prospects of the war. A Defense Department memo identified the primary motivation for continued U.S. involvement as avoiding 'a humiliating U.S. defeat' (70%), with improving life for South Vietnamese cited as a factor in only 10% of the reasoning.
Daniel Ellsberg was one of the study's analysts — a Harvard-educated strategic theorist, Marine veteran, and committed Cold Warrior who had once carried a weapon for the Viet Cong on patrol to understand the enemy. By 1969, his experience in Vietnam had turned him. He photocopied all 7,000 pages over several months using a friend's Xerox machine, sneaking documents out in his children's school bag.
Ellsberg first offered the papers to members of Congress, hoping they would read them into the Congressional Record. None would. He then gave a copy to New York Times reporter Neil Sheehan. The Times began publishing excerpts on June 13, 1971. The Nixon administration — though the papers covered only through 1967, before Nixon took office — immediately sought an injunction. For the first time in American history, the federal government obtained a court order stopping a newspaper from publishing.
Fifteen newspapers eventually obtained copies. The Washington Post, the Boston Globe, and others published simultaneously, making the injunctions impossible to enforce. The Supreme Court heard the case in emergency session. On June 30, 1971 — just 15 days after the Times first published — the Court ruled 6–3 against the government. Justice Hugo Black wrote: 'Only a free and unrestrained press can effectively expose deception in government.'
Nixon's rage over the leak led directly to the formation of a covert White House unit called 'the Plumbers' — tasked with stopping leaks and discrediting Ellsberg. They broke into the office of Ellsberg's psychiatrist looking for damaging personal information. The same operatives and methods would later be deployed against the Democratic National Committee headquarters at the Watergate complex. The Pentagon Papers case thus set in motion the chain of events that ended Nixon's presidency.
Ellsberg was charged under the Espionage Act and faced 115 years in prison. In 1973, the judge declared a mistrial after evidence emerged of the illegal break-in and government misconduct. All charges were dismissed. The Pentagon Papers are now considered a landmark in American press freedom — and a case study in what governments do when the truth about their decisions starts leaking out.