As has been said many times before, the south had every natural right to rebel and the north had every constitutional right to suppress that rebellion. Especially after the south started the shooting. The social contract expressed in the Constitution was broken and the south could no longer claim its protections by their own disavowal of it.
One, there was no rebellion. The Queen of England cannot "rebel" against herself, cannot offend her own majesty.
Against whom, in America, would the sovereign People "rebel" by taking down their Government and substituting another? Get together with Non-Sequitur and let me know, who do the People have to check with before changing their Government, or their laws?
Two, once the Southern States left the Union, the North had no further claims against them save for compensation concerning federal properties and the sharing out and settlement of federal assets and debts.
The North had no claims on the Southerners' allegiance or obedience after secession.
The power to suppress insurrection does not extend to a seceding or seceded State: by definition, the seceding State's People have acted at the supraconstitutional or sovereign level, and the fact that it is the People acting, and not some lesser combination or faction, changes everything. An act of a drunken mob can be insurrectionary. A secession of the People of a State cannot, because secession is sovereign and therefore clothed with legality and the People's power, whereas the insurrectionary mob is not protected by that supralegal, supragovernmental legality.
Especially after the south started the shooting.
They were within their rights to terminate by force the exercise of alien power on their soil. Just as Ohio's Militia would have been within its rights to throw a body of Canadian, French, or Confederate troops off its soil.
The social contract expressed in the Constitution was broken and the south could no longer claim its protections by their own disavowal of it.
I'd have to think about that statement a little more. Of course, the Southern States were no longer in the Union, so on its face your statement looks to be true. The laws of war, and not the Constitution, would have governed, if the United States decided on waging war against its new neighbor.