Name the American President who had to resign when it became clear that he was about to be impeached and convicted by Congress?

Faced with mounting evidence of his involvement in the Watergate cover-up, particularly the release of the "smoking gun" tape on August 5, 1974, Nixon's political support evaporated, and Republican congressional leaders informed him that his impeachment by the House and removal from office by the Senate were all but certain. He announced his resignation in a televised address on August 8, 1974, which became effective at noon the following day.