Margaret "Peggy" O'Neale (or O'Neill, later Margaret O'Neill Eaton) was the daughter of a Washington, D.C. boarding-house owner who had lost her first husband, sailor John B. Timberlake, to suicide. Peggy was renowned for having a "vivacious" temperament — the implication being that she was overtly flirtatious and sexual at a time when "respectable" women, as a group, were not — and it was alleged that Timberlake had been driven to suicide because of her affair with Jackson's Secretary of War John Henry Eaton. Peggy and Eaton were married shortly after Timberlake's death, scandalizing the respectable women of the capital.
The anti-Peggy coalition was led by Second Lady Floride Calhoun, the wife of Vice President John C. Calhoun and a phalanx of other Cabinet wives, while Martin Van Buren, the only unmarried member of the Cabinet, having been widowed, allied himself with the Eatons. Jackson was sympathetic to the Eatons, in part, perhaps, because his own beloved late wife, Rachel Donelson Robards, had been the subject of equally nasty innuendo. (Her first marriage turned out to have not been completely dissolved prior to her wedding to Jackson.) That said, Jackson's First Lady, Rachel's niece Emily Donelson, nonetheless sided with the Calhoun faction.
The scandal was so intense that several members of the Cabinet finally resigned, including Samuel D. Ingham and John Branch, and Van Buren was elevated to a position as Jackson's favorite (replacing Calhoun) and the de facto heir to the Democratic party. Eventually, Eaton also resigned from the cabinet. Emily Donelson was made the "Official Hostess" under Jackson.