(states remaining in the federal union or "the North") and the Confederate states (southern states that voted to secede"the Confederacy" or "the South").[e] The central cause of the war was the status of slavery, especially the expansion of slavery into territories acquired as a result of the Louisiana Purchase On the eve of the Civil War in 1860, four million of the 32 million Americans (nearly 13%) were enslaved black people, almost all in the South
