Just so you are aware, the entire Civil War to end slavery is a lie, like so many others that were taught in our schools. States in the south were preparing to end slavery peacefully through gradual emancipation when they were attacked by John Brown and Nat Turner. Without those two 'abolitionists,' slavery would have likely ended in the south without a shot. While the northern media propped both of them up, their own writings presented a different story of deranged madmen wanting to do things like make an independent country for blacks ... so they could be moved there from everywhere else in the United States.

The main causes were economic. The vast amount of federal revenue came from the rising tariffs on goods from overseas that the southern economy relied on. Their main markets for selling cotton were also overseas, so the south got hit both ways. The majority of money raised through the tariff war against England and the rest of Europe went to prop up northern industrial development and railways.

There were efforts in the south to industrialize, which would have allowed them to get away from slavery even more easily, but railroads placed additional fees on shipping manufactured goods out of the south to the north but placed no such fees on industrial goods going south or raw goods going north to northern factories. The south was going bankrupt and there's records of plantations having to even borrow money from their own slaves to keep in operation due to increasing costs.

The war only started because the Union baited the Confederacy to fire upon Fort Sumter, which was well within it's own borders, to prevent it from being reinforced by more hostile forces. As an additional note, while the more limited role of the Confederate government forbade it from making laws for individual states about what they do about slavery within their own borders under the doctrine of states rights, it could and did immediately outlaw the importation of slaves from overseas ... well before the Union ever did.

Also, the laws about slaves not being counted as a full human? I believe those originated in the north to prevent southern states gaining enough representation to have a say in where the tariff money went. The south wanted all blacks, slave and free, to be counted as full humans as a matter of their economic well being. Additionally, during the war, only the Confederacy had entire black regiments led by blacks. All black regiments fighting for the Union were led by whites.

In the north, you had slavery in the form of wage slaves, immigrants from countries like Ireland who were bated into contracts with absurd terms just to get to America, only to find it impossible to pay off their debt and had no choice but to work in northern factories for abysmal pay while living in ratty apartments that were sub-standard at best. Later, the promise was land for fighting in the war, despite treaties with Indian tribes and other issues.

in the end, it was all a ploy to put the post-war United States in a position where it was in so much debt that it could be taken over and the federal reserve system put in place.