Mary Henderson was born in Warrenton, Virginia to an old antebellum planter family. Her father was an army surgeon who took his family north with him when he was posted to the U.S. Military Academy at West Point, New York. There, at age 17, Mary met and married Captain Seth Eastman, an army officer, painter, and, book illustrator; he provided illustrations for some of her works. In 1841, Eastman was promoted to Brigadier General and assigned the command of Fort Snelling, Minnesota. During this time, Mrs. Eastman wrote her first published work, Dahcotah; or, Life and Legends of the Sioux Around Fort Snelling (1849), which is believed to have inspired Henry Wadsworth Longfellow to write his famous poem, The Song of Hiawatha. Her second novel, Aunt Phillis’s Cabin; or, Southern Life As It Is (1852), was written as a reply to Harriet Beecher Stowe’s novel Unce Tom’s Cabin (1851), and made the typical Southern slaveholders' argument that slavery was more paternal and benign than the life of free black people and the working classes of the urban North. It became one of the bestsellers of the "anti-Tom" movement and sold about 20-30,000 copies. Mrs. Eastman’s other works included The American Aboriginal Portfolio (1853), Chicora and Other Regions of the Conquerors and the Conquered (1854), and Tales of Fashionable Life (1856).