The Watergate scandal was a political scandal in the United States involving the administration of U.S. President Richard Nixon from 1971 to 1974 that led to Nixon's resignation. The scandal stemmed from the Nixon administration's continuous attempts to cover up its involvement in the June 17, 1972 break-in of the Democratic National Committee headquarters at the Washington, D.C. Watergate Office Building. After the five perpetrators were arrested, the press and the U.S. Justice Department connected the cash found on them at the time to the Nixon re-election campaign committee. Further investigations, along with revelations during subsequent trials of the burglars, led the U.S. House of Representatives to grant its judiciary committee additional investigation authority to probe into "certain matters within its jurisdiction", and the U.S. Senate to create a special investigative committee. The resulting Senate Watergate hearings were broadcast "gavel-to-gavel" nationwide by PBS and aroused public interest. Witnesses testified that the president had approved plans to cover up administration involvement in the break-in, and that there was a voice-activated taping system in the Oval Office. Throughout the investigation, the administration resisted its probes, which led to a constitutional crisis.

Several major revelations and egregious presidential action against the investigation later in 1973 prompted the House to commence an impeachment process against Nixon. The U.S. Supreme Court ruled that Nixon had to release the Oval Office tapes to government investigators. The tapes revealed that Nixon had conspired to cover up activities that took place after the break-in and had attempted to use federal officials to deflect the investigation. The House Judiciary Committee then approved articles of impeachment against Nixon for obstruction of justice, abuse of power, and contempt of Congress. With his complicity in the cover-up made public and his political support completely eroded, Nixon resigned from office on August 9, 1974. It is believed that, had he not done so, he would have been impeached by the House and removed from office by a trial in the Senate. He is the only U.S. president to have resigned from office. On September 8, 1974, Nixon's successor, Gerald Ford, pardoned him.

There were 69 people indicted and 48 people—many of them top Nixon administration officials—who were convicted. The metonym Watergate came to encompass an array of clandestine and often illegal activities undertaken by members of the Nixon administration, including bugging the offices of political opponents and people of whom Nixon or his officials were suspicious; ordering investigations of activist groups and political figures; and using the Federal Bureau of Investigation, the Central Intelligence Agency, and the Internal Revenue Service as political weapons. The use of the suffix "-gate" after an identifying term has since become synonymous with public scandal, especially political scandal.

Wiretapping of the Democratic Party's headquarters

On January 27, 1972, G. Gordon Liddy, Finance Counsel for the Committee for the Re-Election of the President (CRP) and former aide to John Ehrlichman, presented a campaign intelligence plan to CRP's acting chairman Jeb Stuart Magruder, Attorney General John Mitchell, and Presidential Counsel John Dean that involved extensive illegal activities against the Democratic Party. According to Dean, this marked "the opening scene of the worst political scandal of the twentieth century and the beginning of the end of the Nixon presidency".

Mitchell viewed the plan as unrealistic. Two months later, Mitchell approved a reduced version of the plan, including burglarizing the Democratic National Committee's (DNC) headquarters at the Watergate Complex in Washington, D.C.—ostensibly to photograph campaign documents and install listening devices in telephones. Liddy was nominally in charge of the operation,but has since insisted that he was duped by both Dean and at least two of his subordinates, which included former CIA officers E. Howard Hunt and James McCord, the latter of whom was serving as then-CRP Security Coordinator after John Mitchell had by then resigned as attorney general to become the CRP chairman.

In May, McCord assigned former FBI agent Alfred C. Baldwin III to carry out the wiretapping and monitor the telephone conversations afterward. McCord testified that he selected Baldwin's name from a registry published by the FBI's Society of Former Special Agents to work for the Committee to Re-elect President Nixon. Baldwin first served as bodyguard to Martha Mitchell—John Mitchell's wife, who was living in Washington. Baldwin accompanied Martha Mitchell to Chicago. Eventually the committee replaced Baldwin with another security man.

On May 11, McCord arranged for Baldwin, whom investigative reporter Jim Hougan described as "somehow special and perhaps well known to McCord", to stay at the Howard Johnson's motel across the street from the Watergate complex. Room 419 was booked in the name of McCord's company. At behest of Liddy and Hunt, McCord and his team of burglars prepared for their first Watergate break-in, which began on May 28.

Two phones inside the DNC headquarters' offices were said to have been wiretapped. One was Robert Spencer Oliver's phone. At the time, Oliver was working as the executive director of the Association of State Democratic Chairmen. The other phone belonged to DNC chairman Larry O'Brien. The FBI found no evidence that O'Brien's phone was bugged; however, it was determined that an effective listening device was installed in Oliver's phone. While successful with installing the listening devices, the committee agents soon determined that they needed repairs. They plotted a second "burglary" in order to take care of the situation.

Sometime after midnight on Saturday, June 17, 1972, Watergate Complex security guard Frank Wills noticed tape covering the latches on some of the complex's doors leading from the underground parking garage to several offices, which allowed the doors to close but stay unlocked. He removed the tape, believing it was nothing. When he returned a short time later and discovered that someone had retaped the locks, he called the police. Responding to the call was an unmarked car with three plainclothes officers (Sgt. Paul W. Leeper, Officer John B. Barrett, and Officer Carl M. Shoffler) working the overnight "bum squad"—dressed as hippies and on the lookout for drug deals and other street crimes. The burglars' sentry across the street, Alfred Baldwin, was distracted watching TV and failed to observe the arrival of the police car in front of the hotel. Neither did he see the plainclothes officers investigating the DNC's sixth floor suite of 29 offices. By the time Baldwin finally noticed unusual activity on the sixth floor and radioed the burglars, it was already too late. The police apprehended five men, later identified as Virgilio Gonzalez, Bernard Barker, James McCord, Eugenio Martínez, and Frank Sturgis. They were charged with attempted burglary and attempted interception of telephone and other communications. The Washington Post reported that "police found lock-picks and door jimmies, almost $2,300 in cash, most of it in $100 bills with the serial numbers in sequence ... a short wave receiver that could pick up police calls, 40 rolls of unexposed film, two 35 millimeter cameras and three pen-sized tear gas guns".

The following morning, Sunday, June 18, G. Gordon Liddy called Jeb Magruder in Los Angeles and informed him that "the four men arrested with McCord were Cuban freedom fighters, whom Howard Hunt recruited". Initially, Nixon's organization and the White House quickly went to work to cover up the crime and any evidence that might have damaged the president and his reelection.

On September 15, 1972, a grand jury indicted the five office burglars, as well as Hunt and Liddy, for conspiracy, burglary, and violation of federal wiretapping laws. The burglars were tried by a jury, with Judge John Sirica officiating, and pled guilty or were convicted on January 30, 1973.