The Civil War was not fought over slavery.  https://www.battlefields.org/learn/primary-sources/declaration-causes-seceding-states (not all of the seceding states published such declarations, but those that did not discussed their reasons in their legislatures.  It’s not as easy linking to those records, but if you spend some quality time in the state archives you’ll see that the issues were the same). https://sourcebooks.fordham.edu/mod/1861stephens.asp (especially the fourth and fifth paragraphs). It’s fair to say that North was fighting to prevent Southern secession as much as to end slavery, but there is absolutely no historical doubt that slavery is why the southern states seceded.