Born into a prominent family, John Henry Eaton was the son of John and Elizabeth Eaton. His father, a chaise maker, was county coroner, a member of the state assembly, and the owner of five thousand acres of land in Williamson County, property he had received from the estate of his uncle, Major Pinkerton Eaton, a soldier killed in the Revolution.
After briefly attending the University of North Carolina, the young John Henry Eaton settled in Tennessee around 1808 and began a law practice in Franklin. He participated in the War of 1812, and in 1813 he married Myra Lewis, the daughter of a wealthy landowner and a ward of Andrew Jackson. He served in the Tennessee legislature in 1815 and 1816, and in 1817 he completed a biography of Jackson, the hero of New Orleans. He entered the United States Senate in 1818, serving until 1829.
Eaton is most famous for his close relationship to an American president and for his marriage to a controversial woman. (His first wife died without issue.) He was one of Jackson's closest advisers in the 1824 and 1828 presidential campaigns, and when Jackson became president in 1829 he named Eaton his secretary of war. On January 1, 1829, Eaton married the daughter of a Washington boarding house proprietor, the recent widow of a navy purser who had committed suicide and a woman who was the target of rumors of sexual improprieties. Washington society women and cabinet wives refused to associate with Margaret “Peggy” O'Neale Timberlake Eaton, so her husband and the president unsuccessfully fought a two-year battle for her acceptance. What began as a social matter turned into a political fray resulting in the break-up of Jackson's cabinet and a permanent split between him and his vice-president, John C. Calhoun.
To make up for Eaton's resignation from the cabinet, Jackson tried but failed to have him reelected to the United States Senate from Tennessee. He then appointed him governor of the Florida Territory (1834-36) and later made him United States minister to Spain (1836-40). Upon his return to the United States, Eaton joined the Whig Party and lost Jackson's friendship until just before the former president's death in 1845. Eaton spent most of his later life in Washington as a prominent attorney, but he and his wife regularly returned to Franklin during the summers. When he died in 1856, his substantial estate testified to a lifetime of financial success.
Ada S. Walker, “John Henry Eaton, Apostate,” East Tennessee Historical Society Publications 24 (1952): 26-43