M James Polk

James K. Polk (1795–1849), the 11th President (1845–1849), presided over significant territorial expansion of the United States. He led the nation during the Mexican–American War, which resulted in the U.S. acquiring California and the Southwest. Polk was a tireless worker who achieved all his major objectives, including reducing tariffs and establishing an independent Treasury.

Interesting anecdote: Polk is often noted as a president who kept all his campaign promises. He vowed to serve only one term and accomplished an ambitious agenda in those four years – and indeed did not seek re-election, leaving office exhausted and dying only a few months later.