Confederates were terrified of what was happening to slavery. - William C. Davis

Legalistic Southerners tried to view the Constitution as a contract. Unfortunately, that viewpoint breaks down when viewed as a lawyer views a contract. There are very few ways to legally break a contract unilaterally.

To the old Union they had said that the Federal power had no authority to interfere with slavery issues in a state. To their new nation they would declare that the state had no power to interfere with a federal protection of slavery. Of all the many testimonials to the fact that slavery, and not states rights, really lay at the heart of their movement, this was the most eloquent of all.

In fact, the state rights defense of secession in 1860–1861 did not really appear in force until after 1865 as builders of the Lost Cause myth sought to distance themselves from slavery.