KANSAS-NEBRASKA ACT (1854). This decision allowed the two new territories to decide for themselves whether to accept slavery or not. Unpopular by both the North and the South, it repealed the Missouri Compromise and the Compromise of 1850; caused the dissolution of several political parties; and further divided the nation.
DRED SCOTT DECISION (1857). This Supreme Court decision declared that slaves (and their descendants) were not Constitutionally protected, and that slaves could not, without due process, be taken from their rightful owners. It also ruled that the Federal government had no right to ban slavery in existing territories. The decision was a short-term victory for the South, and the verdict was extremely unpopular in the North.
JOHN BROWN'S RAID (1959). Abolitionist John Brown's raid of the Harper's Ferry, VA armory was put down by Federal troops, but it caused the South to believe that even more slave uprisings might be coming. Brown's hanging made him a martyr in the North, further strengthening abolitionist discontent.
PRESIDENTIAL ELECTION OF LINCOLN (1860). The election of Abraham Lincoln was the last straw for the South, who believed that Lincoln planned to end slavery in the Southern states. The South's mistrust of the Republican party also contributed to South Carolina's secession shortly after the election.