the South committed a massive act of treason against the United States of America. They did this in defense of slavery. You do not need to take my word for it. Their own secession convention said so. Their own Constitution said so -- in quite explicit terminology. To quote Article 1 Section 9: "4. No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed." That is, slavery was enshrined in the Confederate constitution as an inherent part of what it meant to be a Confederate. If you wanted to abolish slavery because the ownership of other human beings is inherently evil and abhorrent to all civilized men, you weren't a Confederate -- period.
After General William Tecumseh Sherman taught the South the error of their ways, Southerners started claiming that the war was about "state's rights", not about slavery. But if that's so, why does the Confederate constitution explicitly prohibit states from banning slavery within their borders? The "state's rights" thing came about after the war, the secession conventions were mostly silent on the issue, instead containing rant after rant about how the evil North wanted to take their slaves away from them...
Finally, the notion of states with an existence apart from the Federal government would apply to Virginia, North Carolina, South Carolina, and Georgia, which existed before the Federal government. It could even apply to Texas, which was an independent nation for a short period before joining the United States. But it most certainly could not apply to Florida, which was bought from Spain for $5,000,000 in cold hard cash, or Louisiana, Arkansas and Mississippi, which were bought from France for $15,000,000 in cold hard cash, or indeed Mississippi, Alabama, Kentucky, or Tennessee, which were ceded to the United States as territories when the U.S. won the American Revolution and never had any independent existence before that. Those states were effectively purchased with the costs of the American Revolution, which was around $70 million dollars. If those states wanted to be independent at the very least they would have been required to reimburse the Federal government for the expenses incurred in purchasing them from foreign powers in the first place.
But of course no such proposal was ever made on the part of the Confederacy, because it wasn't about states, it was about slavery, and pretending that it was about states wasn't part of the early existence of the CSA. They were quite explicit that it was about slavery... they didn't pretend, they stated it flat out. For example, Confederate Vice President Alexander H. Stephens. In 1861, in Savannah, Georgia, Stephens bluntly declared that slavery was "the immediate cause of the late rupture and the present revolution." He said the United States had been founded on the false belief that all men are created equal. The Confederacy, in contrast, had been "founded upon exactly the opposite idea; its foundations are laid, its cornerstone rests, upon the great truth that the Negro is not equal to the white man; that slavery, subordination to the superior race, is his natural moral condition."
And that "great truth" stated bluntly by Stephens is what's behind the veneration of the Confederacy today amongst white Southerners. Sure, it's about heritage -- a heritage of bigotry and hate against black people. So for the next four years we have to put up with those insufferable bigots claiming that they are not, in fact, bigots, because they're only celebrating their "heritage" of hate, not hate itself. Personally, I'm waiting for April 26, 2015 -- the 150th anniversary of the surrender of the final Confederate army, that of General Joseph Johnston, to General William Tecumseh Sherman. We need to dig up ole' Willy and put him to work again on the South, methinks, just on general principals, maybe if we burn the place flat down to the ground again and built it back from scratch, we can bring civilization to a place that's not had it in the lifetime of anybody living, with the exception of a few pockets of sanity like Austin (which we'll allow to stay unburned). The rest... burn, baby, burn! Yeeehawwww!
-- Badtux the History Penguin