Richardson was Secretary of Defense in the Nixon Administration from Jan 30, 1973 to May 24, 1973.
Elliot L. Richardson held three cabinet positions in the Nixon Administration.
He was Secretary of Health, Education and Welfare, from 1970 to 1973. (It was PNAC signatory Caspar Weinberger who was appointed to the position when Richardson left; Weinberger would become Defense Secretary under Reagan).
In 1973, Richardson assumed the role of Attorney General, taking Richard Kleindienst's place when he was forced to resign as a result of his role in the Watergate scandal. Kleindienst replaced John Mitchell, whose involvement in Watergate led to his resignation. On March 1, 1974 Mitchell was finally convicted of conspiracy to obstruct justice in that scandal).
When ordered by Nixon to fire special Watergate prosecutor Archibald Cox, Attorney General Richardson refused and resigned in protest. So did Deputy Attorney General William Ruckelshaus, who was next in line. Nixon then named Solicitor General Robert Bork acting Attorney General. Bork had no problem with Nixon's order and promptly fired Cox. Members of Congress became infuriated, and within days numerous bills of impeachement against Nixon were introduced. Bork would later be nominated to the Supreme Court by Ronald Reagan. Bork's wife, Ellen Bork, is a PNAC signatory.
After stepping down as Attorney General, Richardson would become Secretary of Defense. He held that position from January 30th of 1973 until May 24th.
After Nixon's resignation, Richardson became Secretary of Commerce in the Ford Administration (1976-77). He would later also act as a special diplomatic representative under Jimmy Carter, George H.W. Bush and Bill Clinton.