The Horse Soldiers is a 1959 American adventure war film set during the American Civil War directed by John Ford and starring John Wayne, William Holden, and Constance Towers. The screenplay by John Lee Mahin and Martin Rackin was loosely based on the Harold Sinclair (1907-1966) 1956 novel of historical fiction of the same name, a fictionalized version of the famous Grierson's Raid by federal cavalry in April–May 1863 riding southward through Mississippi and around the Mississippi River fortress of Vicksburg during the Vicksburg campaign to split the southern Confederacy by Union Army General Ulysses S. Grant.