The American lawyer and statesman John Middleton Clayton (1796-1856) served as U.S. secretary of state during 1849-1850.

John M. Clayton was born in Dagsboro, Del., on July 24, 1796. As a young man, he showed exceptional abilities, and in 1815 he graduated from Yale College with highest honors. After studying law in the office of his cousin and at the famous Litchfield Law School in Connecticut, Clayton was admitted to the Delaware bar in 1819. Soon he became one of the state's leading lawyers and orators.

Clayton served Delaware in a number of offices and became active in national politics in 1824 as a partisan of John Quincy Adams in his battle against Andrew Jackson. Conservative in background and outlook, Clayton became a leader of the Delaware Whig party. In 1828 he was elected to the U.S. Senate and became a noted anti-Jacksonian and a confidant of Henry Clay. In 1833 Clayton was effective in securing passage of Clay's compromise tariff. Reelected to the Senate in 1834, he resigned in 1836. From 1836 to 1839 he was chief justice of Delaware.

In 1839 Clayton supported the presidential candidacy of William Henry Harrison. In 1845, after acquiring a national reputation as a scientific farmer, Clayton returned to the U.S. Senate. He opposed President James Polk's expansionist policies on Oregon and Mexico, although he supported the Mexican War after it began. In 1848 Clayton broke with Clay, supporting the successful presidential candidacy of Zachary Taylor. Taylor appointed Clayton secretary of state in 1849.

As secretary of state, Clayton was intensely nationalistic and an ardent advocate of commercial expansion. But his strict interpretation of international law created unnecessary crises with Spain, Portugal, and France. His interest in commercial expansion was clear in his advocacy of increased trade with the Orient--later implemented by the mission of Matthew Perry to Japan--and his negotiation of the Clayton-Bulwer Treaty in 1850. This treaty won British recognition of an equal American interest in the Central American canal area, and it remained in effect until 1901, when the United States acquired full dominance there.

After Taylor's death in 1850, Clayton resigned his office and returned to his Delaware farm. In 1853 he returned to the Senate, chiefly to defend his treaty with England against attackers who suggested he had yielded unnecessarily to the British. By 1856 declining health rendered him inactive. He died of a kidney disease that year at his home.