The presidency of Richard Nixon began at noon EST on January 20, 1969, when Richard Nixon was inaugurated as 37th President of the United States, and ended on August 9, 1974, when he resigned in the face of almost certain impeachment and removal from office, the only U.S. president ever to do so. He was succeeded by Gerald Ford, whom he had appointed Vice President after Spiro Agnew was forced to resign. Conversely, Black argues that Nixon sincerely believed he could intimidate North Vietnam through the Madman theory. Regardless of his opinion of the war, Nixon wanted to end the American role in it without the appearance of an American defeat, which he feared would badly damage his presidency and precipitate a return to isolationism. He sought some arrangement which would permit American forces to withdraw, while leaving South Vietnam secure against attack. With Nixon's permission, Richardson appointed Archibald Cox as an independent special prosecutor charged with investigating Watergate.