Richard Nixon is best known for his nuclear arm control agreements with the Soviet union and the Nixon doctrine. The Nixon Doctrine is was announced in 1969 and it supported allies facing militarry threats with economic and and military aid rather than with ground troops.
In 1972 President Nixon saw himself involved in what is known as the watergate scandal. The watergate scandal was when Nixon aids hired people to break in the Democratic National Committee offices.
Nixon was forced to resign in 1974 to avoid impeachment. He is best known as the only president to ever resign and the watergate scandal.