Forty-two years ago tonight was the “Saturday Night Massacre,” the beginning of the end for the Nixon administration. Three heads rolled that night: those of Special Prosecutor Archibald Cox, appointed to investigate the Watergate scandal, U.S. Attorney General Elliot Richardson, and Deputy Attorney General William Ruckleshaus. But the head that would roll within a year was that of President Richard M. Nixon.

The massacre was a central piece of the Watergate story, a story that started a year before it. In 1972, Nixon was running so strongly for reelection that he and Vice President Spiro Agnew would eventually win with an astonishing 60.7% of the vote, taking the electoral votes of every state except Massachusetts and Washington, DC. But since winning office in 1968, Nixon had become increasingly paranoid about his hold on power. When Daniel Ellsberg leaked the Pentagon Papers to the New York Times, which began to publish them in June 1971, Nixon became convinced that there was a conspiracy to destroy him. The Pentagon Papers concluded that presidents from Harry Truman to Lyndon Johnson had lied to the American people about the Vietnam War. The study ended before the years of the Nixon administration, but Nixon knew well that there was plenty to leak about his own Vietnam policy. Such exposure would destroy his presidency.

The drive to prevent such a leak led the president and his advisors to create a Special Investigations Unit: The Plumbers. They tried to discredit Ellsberg by stealing files from his psychiatrist. Then they turned to bigger fish: they tried to sabotage Nixon’s political opponents. They planted fake letters in newspapers and planted spies in Democratic organizations. Finally, on June 17, 1972, they tried to wiretap the headquarters of the Democratic National Committee in Washington’s fashionable Watergate complex.

The Watergate security guard noticed that doors were wedged open and called the police, who arrested five men trying to take photographs of documents and bug the office. Immediately, the White House denied all knowledge of what it called a “third rate burglary attempt.” While most of the press took the denial at face value, two young reporters for the Washington Post, Bob Woodward and Carl Bernstein, followed the sloppy money trail behind the burglars and discovered tracks that ran directly to the White House. But confirming a connection proved difficult. Even after the story broke, Nixon won triumphant reelection.

The administration’s story began to unravel in March 1973, when one of the burglars told a judge that he and his co-defendants had perjured themselves. Immediately, White House counsel John Dean turned state’s evidence. In the next month, three of Nixon’s top advisors resigned, and the president was forced to appoint prominent attorney Archibald Cox as a special prosecutor to investigate the affair. The following month, the Senate began televised hearings on the growing scandal. The hearings uncovered the astonishing fact that Nixon had taped his conversations.

When Cox subpoenaed a number of those audiotapes, Nixon fired him on October 20. In the Saturday Night Massacre, Attorney General Elliot Richardson and his deputy William Ruckleshaus resigned in protest of Cox’s termination. Nixon then turned to the Solicitor General, the third man at the Justice Department, to carry out his orders and fire Cox. (That man was Robert Bork, who would be nominated for the Supreme Court in 1987 by Ronald Reagan, only to have the Senate reject his nomination.)

The Saturday Night Massacre swung popular opinion toward the impeachment of the president. Within a month, Nixon felt it necessary to assure the American people: “I am not a crook.” He was forced to allow Bork to appoint a new prosecutor, Leon Jaworski, who fought for access to some of the crucial tapes and won a unanimous decision from the Supreme Court giving it to him. Nixon’s people finally released transcripts of the recordings. They were damning. Not only did they reveal an administration consumed by paranoia and revenge, they showed the president to be a mean-spirited, foul-mouthed thug. Aware that the tapes would not play well with the public, Nixon had his profanity redacted. “[Expletive deleted]” entered the American lexicon.

The House of Representatives began to draw up articles of impeachment, charging the president with obstruction of justice, abuse of power, and contempt of Congress. When a new tape revealed that Nixon and an aide had plotted to protect the White House from the Watergate scandal only days after the break-in, the gig was up. On August 9, 1974, Nixon became the first president in American history to resign.

In the end, the Saturday Night Massacre claimed not three men, but four.