John Spencer was born in Hudson, New York, on January 8, 1788. He attended Union College in New York, where he graduated in 1806. After serving as private secretary to New York governor Daniel D. Tomkins form 1806 until 1808, Spencer was accepted to the New York bar in 1809. He went on to become the master of chancery at the U.S. Court of Equity (1813). From 1816 until 1818, he served as a delegate to the U.S. House of Representatives, following which he served in the New York State Assembly (1820-1822) and Senate (1825-1828). He rounded out his New York political career as secretary of state (1839).Spencer became President John Tyler's secretary of war on October 12, 1841, and held that post until March 3, 1843. He would also serve Tyler as secretary of the treasury (March 8, 1843-May 2, 1844). During his time in the cabinet, Spencer was a fervent opponent of admitting Texas to the Union as a slave state. He died on May 18, 1855.