Richard Nixon had long opposed efforts by both the Judicial system and Congress to investigate his involvement in the Watergate Scandal. His most infamous act was the "Saturday Night Massacre" in which he fired his Attorney General and Assistant Attorney General and the Special Prosecutor, Archibald Cox in an attempt to subvert a subpoena seeking tapes of conversations Nixon held in the Oval Office. When copies of the tapes were ultimately made available, evidence was overwhelming that Nixon had learned of the Watergate break-in shortly after it happened, and was part of a plan to hinder investigation of the burglary.
On the basis of this information, the Judiciary Committee of the House of Representatives voted Articles of Impeachment on July 27, 1974.:
RESOLVED, That Richard M. Nixon, President of the United States, is impeached for high crimes and misdemeanours, and that the following articles of impeachment to be exhibited to the Senate:
In his conduct of the office of President of the United States, Richard M. Nixon, in violation of his constitutional oath faithfully to execute the office of President of the United States and, to the best of his ability, preserve, protect, and defend the Constitution of the United States, and in violation of his constitutional duty to take care that the laws be faithfully executed, has prevented, obstructed, and impeded the administration of justice....
In all of this, Richard M. Nixon has acted in a manner contrary to his trust as President and subversive of constitutional government, to the great prejudice of the cause of law and justice and to the manifest injury of the people of the United States.
Wherefore Richard M. Nixon, by such conduct, warrants impeachment and trial, and removal from office.
Although Constitutional procedure calls for a trial before the Senate, the trial never took place. Nixon was informed that only fifteen Senators would vote for his acquittal. The minimum he needed to escape removal from office was thirty four. In the face of this information, Nixon knew he was doomed, and on August 8, 1974 in a nationally televised address, Nixon informed the nation that he would resign the Presidency at noon the following day. Immediately following his resignation, Gerald Ford was sworn in as President. Since Ford himself had been appointed (not elected) to the office of Vice President, he became the only President of the United States who was unelected.