On Oct. 20, 1973, President Richard Nixon set off one of the most dramatic nights of the Watergate scandal, according to HISTORY and PBS's American Experience.

Archibald Cox, the Watergate special prosecutor, had been running a detailed investigation of the break-in at the Democratic National Committee's offices in the Watergate complex in Washington, HISTORY reports. His work suggested the burglary was just one of many possible abuses of power by the Nixon White House.

Nixon ordered Attorney General Richardson to fire Cox. Richardson refused and resigned, HISTORY reports. Nixon then asked Deputy Attorney General Ruckelshaus to dismiss the special prosecutor. He also refused and resigned.

The order then fell to Solicitor General Robert Bork. He agreed and fired Cox, HISTORY reports. Taken together, the firing and the resignations became known as the "Saturday Night Massacre."

The public and the press were outraged, according to HISTORY. Congress filed 21 resolutions calling for Nixon's impeachment, PBS's American Experience reports. Two days after the firing, the House Judiciary Committee began to look into whether Nixon should be impeached, HISTORY reports.

The pressure did not let up after that night. Investigators eventually learned that the cover-up of the break-in reached into the White House itself. Facing impeachment, Nixon resigned the presidency in August 1974, HISTORY reports.

The firing did not end the inquiry. It became one of the best-known moments of the scandal, and it is still used as shorthand for the night two top law officers quit rather than obey the president.

What we know: On Oct. 20, 1973, Cox was fired and the two top Justice Department officials resigned rather than fire him.
What we don't: How events would have unfolded if Bork had also refused to carry out the order.