The South wasn't a bunch of innocents, for sure, but the question we need to raise is, did he need to wage war? if you think that he did, then I would argue you haven't studied history enough. Why did chattel slavery end everywhere else before and after the Civil War without a war?

I believe revoking the Fugitive Slave Act and letting the South secede would have ended slavery in the same way it did in Brazil, through economic means and without millions of deaths.