Comment by shadowgovt

I think people frequently forget that the North didn't actually have the firepower to stamp out the ideology.

Like any ideology, you can't actually destroy it with force any other way than burning books and, eventually, men.

And whether or not that would have been wise: the war was extremely costly for the North and there was a non-zero chance that if they started dropping every third Southerner from the gallows the federal government would lose legitimacy in the eyes of the survivors on both sides of the Mason-Dixon and that'd be it.