ON SECESSION: Eugene Volokh, whose blog I might well be adding on the left presently, has some interesting posts up on the matters of secession and slavery. (Also scroll down a bit to see the original posting about Confederate flags.) I agree with Volokh in the main, but I think him fundamentally wrong about the ACW and its meaning.
The ACW was, ultimately, about two things. First, slavery, and second, state's rights; in particular, the question of the right of a state to secede from the Union. The North claimed there was no such right. The South thought there was. I think there was, and is, such a right. In that reading, the North was wrong. Wrong to attack the South; wrong to start a war at all. Now, if the North had started the war over slavery, then I would have to say they were justified, or at least, that they had a plausible justification for war. But they did not. They started the war only for the "Union", which was a rather tenditious way of asserting the idea that no state could leave the Union and any trying to do so were traitors, and must be literally conquered and forced back into it.
But this notion flies against two key founding notions of our republic: federalism (meaning the doctrine of enumerated granted powers), and the notion that the "right" to govern rests on the consent of the governed. These things should be obvious to any conservative or libertarian, I should think. So for Volokh to refer to the Confederate flag as "a symbol of... treason" is simply wrong. It is a symbol of chattel slavery, and of cultural identity, and of valorous resistance to tyranny, and of (yes) freedom. Obviously it is a complex symbol, but surely not wholly devoid of value. (As one can see on the left, I do not fly it myself. I prefer the Gadsden flag.)
The South, in the events of 1861, was right, though, motivated by evil reasons. (And some good reasons, that is, shaking off the oppressive tariffs that Volokh talks about. But I don't think that is the main reason.) The North was motivated, at least in part, by a good reason (anti-slavery), but in their actions they were wrong. In this, we see a similarity to many other hard decisions about liberty. Consider the "classic" case: do Nazis have the rights of free speech? We hold that they do, in spite of the offensiveness of their speech. They are wrong, but they are right to speak, and that is what is at issue. Or, do people have the right to load their bodies full of drugs and poison? A libertarian would say yes, in spite of the negative effects that doing so may have. Must religious artifacts and propaganda be removed from all public display? Yes, in spite of how objectively good such display might be for the body politic. Can we carry about, concealed or revealed, a weapon, with no permission from anyone? Yes, in spite of the danger this poses to others.
It is the hard cases that are most useful in revealings people's political beliefs.
Now, the above reasoning, I would think, would hold true for just about any libertarian. But I want to add on one more point, coming more from the anarchist perspective. And that is, that of all rights one might hold dear to prevent a political system from turning tyrannous, the right of exit is perhaps the most dear. If you can secede from a polity effectively, then you hold the ultimate trump card when it comes to limiting the depredations the polity can inflict upon you. This right is more important than a free press, and more important than the right to keep and bear arms, for if exit is still possible then the violation of those rights would be good grounds to do so. (Of course, the RKBA in particular is designed to make revolution practical; but it would always be better to secede peacefully than not.)
So, to the anarchist inclined libertarian (as they are at lewrockwell.com), the ACW and its defacto outcome -- that there is no right of secession -- is not just a grevious blow to our rights, but rather the blow, the killing blow, that made all the subsequence blows possible. Looked at in that light, the side effect of the ACW -- freeing the slaves -- seems like it is not worth the price. The North freed a minority from a terrible form of slavery, but at the price of subjecting all of us to a milder form of slavery. Of course our subjugation to Washington was initially not bad, merely the launch off the top of the slippery slope. But now we are subject to taxes, conscription, victimless incrimination, inflation, and restrictions of all our rights. And we have not seen the end of it yet. How bad will it be? Who can say?
Meanwhile, most every other country in the world freed its slaves peacefully, so there is at least some reason to believe that the slaves would have been freed, eventually, without any war at all. Indeed, American slaves were not fully freed by the war. It took another 100 years and the slow, patient, peaceful efforts of the civil rights movement to fully effect that goal.
Now, reasonable people can disagree about the relative value of ending chattel slavery versus the loss of the right of secession. But right now, in the popular press and the state run school system, the latter loss is not mentioned at all; and so the ACW is depicted in a cartoonish fashion as fight of the virtuous slavery-abolishing North versus a traitorous South fighting only for evil. It's a lot more complicated than that.