So why did the North go to war?
> So why did the North go to war?
Because the South attacked the Federal troops on the Federal base at Ft. Sumter. When attacked, you either fight back, you ignore it or you roll over. Americans aren't the French, so rolling over wasn't an option. Ignoring a sizable military attack by traitors also isn't much of an option, unlike, say, a Cuban soldier taking a random pot-shot into Gitmo might be ignorable.
Had the Southerners not started their war of aggression, then the FedGuv would have had little cause to war against them... as the fact that secession had been a reality for quite some time and there had been no military attacks by the North proves. The CSA would have secceded, most likely failed as a nation, and then we'd have moved on from there in some way. Reconciling the democratic republicanism of the North with the feudal society of the South in a peaceful alternate history would have been interesting...