Dittos to what you said, but I'd be a little harder. Nearly all the Southern legislatures were controlled lock, stock and barrel by the big slaveholders.
Some claim the war was an economic war of the industrial North against the agricultural South as if the agriculture side was a bunch of small farmers. That is nonsense. The controlling forces in the South were major landholders who had personal wealth that rivaled any Northern industrialist and millions to gain from the expansion of slavery. The Southern wealth was gained with the chain, the lash, the blood, and the freedom of other humans. That is a fundamentally un-American system and after ‘four-score and five’, the charade that it was “American” could no longer be entertained. The South had no moral or constitutional ground the stand on so they resorted to force. Despots always do resort to force, and Slavers, no matter what their excuse is, are always despots.
BTW, have you seen this: "No Gettysburg - An Alternative History." I hardly know what to make of it, though it's clear that the author spent a lot of time on it. He captures the expansionist, imperialist and militarist tendencies that were present in the Confederacy underneath the libertarian rhetoric and Jeffersonian veneer, but he overestimates the degree of social stability that the Confederacy, or for that matter the US, would have had, if the war had gone differently. He supposes that, contrary to many neo-confederates, slavery would not have been abolished by the victorious CSA on the end of the war, but underestimates the costs of letting slavery live on for generations.
A time-waster to be sure, but some may be interested.