William Learned Marcy (December 12, 1786 – July 4, 1857) is an American lawyer, politician, and judge who serves as U.S. Senator, Governor of New York, U.S. Secretary of War and U.S. Secretary of State.
In the latter office, he negotiates the Gadsden Purchase, the last major acquisition of land in the continental United States.
Born in Southbridge, Massachusetts, Marcy establishes a legal practice in Troy, New York after graduating from Brown University.
He fights in the War of 1812, serving as a captain of volunteers
Politically, he aligns with the Bucktail faction of the Democratic-Republican Party and becomes a leading member of the Albany Regency.
As the Democratic-Republicans fractures in the 1820s, he becomes a member of the Democratic Party.
Between 1821 and 1831, he successively serves as Adjutant General of New York, New York State Comptroller, and as an associate justice of the New York Supreme Court
In 1831, the New York legislature elects Marcy to the U.S. Senate, and he holds that position until 1833, when he becomes the Governor of New York.
He serves three terms as governor until his defeat in 1838 by the Whig nominee, William Seward.
He serves as Secretary of War under James K. Polk from 1845 to 1849, overseeing the Mexican–American War. After leaving the Polk administration, he resumes the practice of law and becomes a leader of the "Soft" Hunker faction of the New York Democratic Party.
He returns to the Cabinet in 1853, serving as Secretary of State under Franklin Pierce.
In this role, he resolves a dispute about the status of U.S. immigrants abroad and directs U.S. diplomats to dress in the plain style of an ordinary American rather than the court-dress many had adopted from Europe. \
He also negotiates a reciprocity treaty with British North America and the Gadsden purchase with Mexico, acquiring territory in present-day Arizona and New Mexico.
He leaves office in 1857 and dies shortly thereafter.
