Some southern states seceded when Lincoln was elected in January 1861; first South Carolina, followed quickly by Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas. They created a Confederate government in February, and that government began demanding the handover of Federal forts. President James Buchanan ( who was a southern sympathizer) refused but temporized, and the Confederacy began seizing them. Lincoln was inaugurated in early March, and pledged that he was not trying to end slavery in states where it already existed, and though he would oppose secession he hoped to resolve it peacefully.

Unlike the "fire-eaters" of South Carolina, the states of Virginia, North Carolina, Tennessee and Arkansas were divided in opinion, with some voters and state politicians being in favor of secession, but many wanting to stay in the Union. The Southern states had also been able to wring great concessions from the North in the past, often with threats , and given Lincoln's pacific inaugural address there was good reason to hope that the threat of secession would again make the North want to come to terms again favorable to the South, and Lincoln would be forced to discard any notion of ending slavery in the US. However, instead of that, after a blockade and standoff of more than a month Ft Sumter was shelled and surrendered. In response on April 15 Lincoln called up 75,000 troops of the state militias to suppress the rebellion. In reaction to that mobilization of soldiers, very quickly many southern legislators who had stated they did not want secession switched their votes and those states seceded- it was clear that the North was not going to back down. And the war was started.

It should be noted that there were also divisions in the slave-holding border states of Kentucky, Missouri, Maryland and Delaware, and that it would not be until June 1861 ( after both active diplomacy and military pressure) that they voted to stay within the Union.