You say that the South went outside of the Constitution to Secede, and I still maintain that they seceded under the (key word here Yankee) original principles of liberty as were expressed in the Declaration of Independence, and that we still hold as inviolate!
If you are of the belief that the Declaration of Independence is not valid as a cornerstone of our principles of American liberty, then you must be saying that the States should have petitioned the Federal Government to leave. The Federal Government (overstepping its bounds) would never have let them do so. This would directly affect the individual liberties and pursuit of happiness within each State. 'The powers delegated by the proposed Constitution to the federal government are few and defined. Those which are to remain in the State governments are numerous and indefinite. The former will be exercised principally on external objects, as war, peace, negotiation, and foreign commerce; with which last the power of taxation will, for the most part, be connected. The powers reserved to the several States will extend to all the objects which, in the ordinary course of affairs, concern the lives, liberties, and properties of the people, and the internal order, improvement, and prosperity of the State. Federalist papers No. 45 - Madison
So now you are telling me that the North was justified in invading the South, BUT if you read the Federalist Papers you would find that you are wrong again. 'The American philosophy and system of constitutionally limited government contemplates that the people of the several States--acting through their State governments--will, in last resort, use force to oppose any force employed by the Federal usurpers, that they will use military force (Militia of the States) to oppose any military force used by such usurpers; as Hamilton and Madison explained in detail in The Federalist, numbers 28 and 46.
Power being almost always the rival of power, the general government will at all times stand ready to check the usurpations of the state governments, and these will have the same disposition towards the general government. The people, by throwing themselves into either scale, will infallibly make it preponderate. If their rights are invaded by either, they can make use of the other as the instrument of redress. ' Federalist Paper #28 - Hamilton
'Were it admitted, however, that the Federal government may feel an equal disposition with the State governments to extend its power beyond the due limits, the latter would still have the advantage in the means of defeating such encroachments. If an act of a particular State, though unfriendly to the national government, be generally popular in that State and should not too grossly violate the oaths of the State officers, it is executed immediately and, of course, by means on the spot and depending on the State alone. The opposition of the federal government, or the interposition of federal officers, would but inflame the zeal of all parties on the side of the State, and the evil could not be prevented or repaired, if at all, without the employment of means which must always be resorted to with reluctance and difficulty. On the other hand, should an unwarrantable measure of the federal government be unpopular in particular States, which would seldom fail to be the case, or even a warrantable measure be so, which may sometimes be the case, the means of opposition to it are powerful and at hand. The disquietude of the people; their repugnance and, perhaps, refusal to co-operate with the officers of the Union; the frowns of the executive magistracy of the State; the embarrassments created by legislative devices, which would often be added on such occasions, would oppose, in any State, difficulties not to be despised; would form, in a large State, very serious impediments; and where the sentiments of several adjoining States happened to be in unison, would present obstructions which the federal government would hardly be willing to encounter.' Federalist Papers #46 - Madison
No, I'm saying they should have ammended the Constitution to allow states to leave the Union. If they could not convince their fellow citizens to do this, then they are out of luck. You are trying to ignore the Constitution by wrapping your arguments with the Declaration of Independence. It is rather offensive. Resorting to arms when you have not exhausted every legal means of resolving a conflict of this nature is not responsible. Read the Declaration of Independence more carefully and see how long, and how hard the colonists tried to reconcile with Britian before they declared their independence. Look at the long line of abuses suffered, and tell me how this compares with what the South was suffering. As for putting down the South's insurrection, that is explicitly within the power of the federal government, as listed in the Constitution, which all the Southern states accepted when they joined the Union.
Wasted, though not your fault, it is what happens when one casts pearls before swine.