Replies

Lincoln had vowed to only oppose the expansion of slavery into the Western territories and to leave it alone in states where it was already being practiced. Whether he was telling the truth, we will never know, since as soon as an election went a way they didn't like, the Southern states just up and left, several before Lincoln had even been sworn in! They had no legitimate grievances upon which to base secession.

Or, rather, no grievances that would be appealing to modern apologists attempting to shoehorn in a modern political scene into the era. Many of the things that popped up concerned the internal affairs of other states (Southern states took a dim view of Northern states allowing abolitionist papers to be published freely, or their ignoring the Federal fugitive slave laws, or not recognizing slave ownership within their own territory), and that shouldn't have been their business under the doctrine they were supposedly advocating. The declarations of secession of many Southern states explicitly name this fact (Northern state's disobeying Federal pro-slavery legislation) as a major point for leaving the Union.