Everything for the south revolved around the protection, perpetuation and expansion of slavery.
Everything.
The old tired chestnut of the Corwin Amendment doesn't go very far.
It was a last ditch effort, which most all knew stood no chance of survival.
Lincoln had nothing to do with its passage. By the time he addressed it, most states had already seceded. It was a futility, and most all saw it as such.
At that point too - the south had already commenced hostilities. They were bound and determined to go to war and nothing was going to stop them.
The Southrons made it clear in their many declarations of independence and in a boatload of other statements, actions, laws and their own written constitution, the protection of Slavery was at the base of all.
It was the lifeblood (literally) of their economy, and they knew it.
Wrong on all counts.
The South tried desperately to reach a compromise with Dishonest Abe. Jeff Davis repeatedly asked that the South be allowed to separate without bloodshed. The South agreed to pay their share of the national debt and pay for all federal installations, but Abe told them to fuck off and refused to even meet with them when they came to Washington.
The abolitionist movement had become radicalized and infiltrated by powerful wealthy northern industrialists, who got Dishonest Abe elected. In part, thanks to that stupid book Uncle Tom's Cabin. They were pushing for war so they would not only benefit nicely from war production, but also the imposition of the tariff after the South was defeated.