It was for a very particular reason in their instance, one which they weren't shy in expressing. Alas, Providence did not smile on their designs, and understandably.
Secession to secure the fruits of liberty is not politically analogous to secession in order to secure the power to enslave other human beings. The ends are not ennobled by the means.
Well said, sir!
I think a picture of some American heroes is called for here: