Some in the Southern states argued slavery was threatened. Others pointed out they would be much better off financially if they were independent.
There is no escaping from the facts that the Northern states were quite willing to protect slavery effectively forever and the original 7 seceding states turned down their offer. Clearly something other than concerns over slavery must have been motivating them.
Having already announced their secession and adopted a constitution that protected slavery to a far greater extent than the Corwin amendment ever would have, do you honestly expect that the southern states would then have called it off?
Clearly something other than concerns over slavery must have been motivating them.
Apparently not, if the writings of the southern leaders of the time is to be believed.