A state or states can be as peaceful as the want about leaving but I’m telling you that whatever asshole is sitting in the oval office is going to see that as his/her moment to be held up in history as the next Lincoln and will spill as much blood as needed to bring a rebel state back under control. You think brutal things like the NY draft riots and Sherman’s march to the sea have been bred out of us just because it’s 2013?
Dog, I hate to be so blunt, but you're just flat out wrong about that.
If a state were in the process of gathering men and arms to militarily oppose the federal government, then it stands to reason that a sitting President, the Congress, and the people, would support deployment of the U.S. military to stop it. I have no doubt that they would.
A state that simply intends to peacefully severe it's political bonds with the union will not receive any such response. No President, Congress, nor the people, would have the will to murder their own countrymen in order to force them to remain in the union under those circumstances.
Even in 1861, it took the underlying cause of emancipating the slaves to motivate the northern states to crush the southern rebellion. Slavery was an affront to God and the Constitution, and an enormous sin against mankind. It was right to end it, even if it took force to do so.
Without the issue of slavery attached, it's doubtful that Lincoln could have persuaded the rest of the country to make war on the secessionist South. There's no doubt he would have tried, but I don't think the North would have had the heart to maintain a vigorous military campaign of death and destruction against their southern neighbors over secession alone. The moral issue of slavery was what propelled them forward.