The document summarizes key events leading up to the American Civil War around the issue of slavery. It discusses the Missouri Compromise of 1820 which balanced the number of slave and free states. It also discusses subsequent compromises in 1850 and 1854 regarding the status of slavery in western territories which temporarily delayed the conflict over the issue. Rising tensions and conflicts ultimately led to southern states beginning to secede from the Union after the election of Abraham Lincoln in 1860, marking the start of the Civil War.