The day on which Donald H. Rumsfeld (born July 9, 1932) was sworn in as the Ford administration's Secretary of Defense. Rumesfeld was 43-years-old at the time, making him the youngest US Secretary of Defense to-date.
November 23, 1987:
The day on which Caspar W. Weinberger (born August 18, 1917) resigned as the Regan Administration's Secretary of Defense. At the time, Weinberger was 70 years, making him the oldest US Secretary of Defense to-date.
March 21, 2003:
The day on which Rumsfeld earned the distinction of becoming the youngest and oldest US Secretary of Defense to-date.