It’s simple. The South was getting richer than the North. This war was never fought about slavery. It was fought about economics and power.
“The South was getting richer than the North”
That’s almost right, but I’d put it this way. The South could’ve thrived alone, whereas without the tariff northern industry would’ve collapsed. A free trade zone in the South was deadly to Republican interests, which is why they made their stand at the major Atlantic seaport at Charleston and why in hus first innaugural Lincoln gave them a choice between taxes and war.