Slavery had long divided the politics of the United States. In time, these divisions became both sectional and irreconcilable. The first and most ominous sign of a coming sectional storm occurred over debates surrounding the admission of the State of Missouri in 1821. As westward expansion continued, these fault lines grew even more ominous, particularly as the United States managed to seize even more lands from its war with Mexico. As the country seemed to teeter ever closer to a full-throated endorsement of slavery, however, an anti-slavery coalition arose in the middle 1850s calling itself the Republican Party. Eager to cordon off slavery and confine it to where it already existed, such sentiment won presidential election of 1860 and threw the nation on the path to war.
Throughout this period, the mainstream of the anti-slavery movement remained committed to a peaceful resolution of the slavery issue through efforts understood to foster the “ultimate extinction” of slavery in due time. But as the secession crisis revealed, the South could not tolerate a federal government working against the interests of slavery’s expansion and decided to take a gamble on war with the United States. Secession, in the end, raised the possibility of emancipation through war, a possibility most Republicans knew, of course, had always been an option, but one they nonetheless hoped would never be necessary. By 1861 all bets were off, and the fate of slavery depended upon war.