IMO, the war was principally one of economics in that the North wanted to keep agricultural South as its own for better terms, dictated prices and in a captive-producer situation. They didn’t want the South to sell produce to other countries and their majority legislation made it difficult for the South.
To complicate things, slavery was used as moral tool even through the majority of farmers, etc. in the South didn’t own them - couldn’t afford them. Slavey was for big plantations and rich Southerners.
To have a Second Civil War today would be difficult because there isn’t just one Ft. Sumpter. There are dozens. Name any Democrat city in the South.
otoh you cannot ignore south carolinas declaration of indepence specifically names slavery as a key reason for their leaving the union.
The civil war didnt happen over night, nor was it just about the outlawing of slavery.
Ill just say if the south would have known what was going to happen, they would have picked their own cotton.
And if they had, the north would have still tried to crush the southern states will to be independent of northern rule thru legislation and economic strangulation.