The decision ofÂ southern states to secede from the Federal Union was largely a response to the threatenedÂ abolition or restriction of slave labor, which underpinned many of these states' social and labor systems. Although initially uncomfortable with the idea of complete secession, John C. Calhoun (the slave states' principal spokesman) grew in confidence following the Mexican War and the land acquisitions thereof.
Calhoun's death, however, led to a calming of tensions between the North and South, and a compromise was established allowing many southern states to retain their slave labor laws.
It was when the question arose of whether Kansas should enter the Union as a slave state or a free state that the threat of secession was again invoked. Southern leaders feared that emancipation was again a possibility, particularly following a Republican victory in 1860. South Carolina was the first state to declare its commitment to secession if the Republican party took office. While some other states felt it prudent to wait and see what stance the new government would take on slavery, all were in support of secession as a legitimate response to its interference.
Abraham Lincoln, after taking office in 1861, actually attempted to make a new compromise with border states, allowing lawful slavery to continue. However, the prospect of starting a new and separate nation, free of any northern interference, galvanized many southern states behind the Confederate government.