Slavery was practiced by several Northern states as well (Kentucky, Maryland, Delaware, and New Jersey). The South had every right to secede, and would have done so peacefully if the tyrant Lincoln had simply allowed it.
WWII is not as black-and-white as many make it out to be. Although we were in fact attacked by Japan, it is also true that FDR did everything he could to maneuver them into doing so. This is why the Neocon's--FDR fans every one of them--are so enamored of the idea of a "Pearl Harbor like event" to justify expanding their foreign wars.