On Dec. 19, 1860, a convention of delegates were called to St. Andrew's Hall in Charleston, S.C., to vote on secession. On that day, many issues were brought to the floor to be settled before the actual vote could occur. Among these issues were what to do with the federal military installations in South Carolina, particularly Forts Moultrie and Sumter. It was agreed that all federal property would have to be handed over to the government of South Carolina. Finally, on Dec. 20, 1860, the delegates voted by a count of 169-0 in favor of secession, and the union between South Carolina and other states of the United States was "hereby dissolved."
Between Jan. 9 and Feb. 1, 1861, six other Southern states followed suit: Mississippi, Florida, Alabama, Georgia, Louisiana and Texas respectively. This was the first wave of secession. Then following the inauguration of Lincoln, the second wave began on April 17 with the secession of Virginia. This wave was continued by Arkansas, Tennessee and North Carolina respectively. The only slave-holding states that did not leave the Union were Missouri, Kentucky, Maryland and Delaware. These states were then known as the border states: those that remained loyal to the Union and separated the United States from the newly formed Confederacy.
It was the secession of the Southern states that ultimately led to the first shots of the American Civil War. Lincoln believed secession to be unconstitutional, and therefore not possible. He saw the South's attempt to do so as a rebellion, and he vowed to preserve the Union at all costs. Lincoln also refused to relinquish control of the federal forts on South Carolina. Thus, on April 12, 1861, South Carolina militia, commanded by P.G.T. Beauregard, fired on Fort Sumter, beginning the Civil War. Sumter surrendered on April 14.
Sources Used: Ordeal By Fire: James MacPherson, 1992.
Brother Against Brother: The War Begins: William C. Davis, 1983.
The American People: Gary B. Nash, 1990.