How about we check in with Jefferson Davis about the reason secession might be justified, or necessary?
You remember Davis, right?
1849
" ...There had been a war of seventeen years standing against the institutions of the South, a war whose weapons were both wounding and insulting. As opinion had been formed, authorized by our long supineness on this subject, that we have no sufficient feeling to perceive or to resent the attacks made upon us.
Men of another section are loud in their advice that there is
no danger--that action now would be hazardous or useless, and that the generosity and philanthropy of the North will always prove a sufficient safeguard to Southern rights; but such advice is the lulling of the vampire fawning the victim which he will destroy.
Every compromise has been to our loss, as witness that of the North-western territory and that of Missouri. We have yielded thus far and the results have been that upon our tame submission is now based the demand that we yield the remainder. The equality left by our fathers is to be destroyed.
Give to the North what is now demanded, and soon we shall find a preponderance of three-fourths against us; the constitution of the United States will be changed and all that is now promised to the South will be forgotten. Submit to the loss of this territory, and we shall have next to submit to the abolition of slavery in the District of Columbia,
and soon the constitution will be changed and slavery abolished."
The fear of the South was that it would be overwhelmed by an eventual anti-slavery majority in Congress and then could not resist a legislative/Consitutional eradication of slavery.
Speech at Jackson Miss. May 7 1849 Rice University The Papers of Jefferson Davis