Show me your math. How many upper South states would they have to flip before they could pass a constitutional amendment to ban slavery?
The secessionists recognized the Corwin Amendment as a last minute attempt to hold the country together.
If they would just wait till all or most of the slave states left, they could quickly pass an amendment to ban slavery.
Of course, when given the chance, they immediately tried to pass an amendment to protect slavery.
That wasn't the point. The slave states feared that Republicans in the Border States could abolish slavery in those states and the next step would be for Republicans to build a party in the Upper South that would abolish slavery there. This was seen by the Deep South states as a threat to slavery. No constitutional amendment would have been necessary. If it seems unlikely that Virginia or Tennessee would ever abolish slavery on their own, slaveowners were frightened and convinced that the Republicans were out to get them.
Like Illinois, where you could sell any black person into slavery if they didn't have their paperwork proving they were free?
How often did that happen? There were free blacks in Illinois. Their chief fear was being kidnapped and taken to Missouri and sold into slavery.
My reference was to the "personal liberty laws" that Vermont, Connecticut, Rhode Island, Massachusetts, Michigan, Maine, Wisconsin, Ohio, and Kansas and possibly other states had passed requiring a court hearing (due process) for runaways and others before they could be taken South and made slaves.
The idea that slavery was more secure inside the Union than outside of it wasn't shared by the secessionists. When they wrote their constitution they included explicit protections for slavery. They were convinced that secession would keep meddlesome Yankees out. They certainly would have been willing to fortify the border, especially if they were able to hold Kentucky and make the Ohio River the border.
Anyway, I keep telling you: talk to a reputable historian or economist who could straighten you out. You're starting to sound like those people who are convinced that Hitler wanted peace but the English and the Poles wouldn't let him have it.