The War was about STATES RIGHTS more than anything else, Slavery was just the vehicle.
Imagine if, instead of telling states they cannot have slaves, the were fighting to prevent the Federal Government from telling you you HAD TO buy health insurance or face a fine?
Only when southern states rights were involved. The southern states begged the Federal government to enforce the fugitive slave act at the tip of a bayonet if necessary because northern states were exercising their “states rights” in refusing to return run away slaves to bondage in the south.