On that I will agree. There is a natural right of rebellion But that doesn't mean that the parties rebelled against are under some obligation to simply roll over and allow their nation to be dismembered. Rebellion is a roll of the dice, not some automatic victory.
I return my thanks for the copy of your late very powerful Speech in the Senate of the United S. It crushes "nullification" and must hasten the abandonment of "Secession." But this dodges the blow by confounding the claim to secede at will, with the right of seceding from intolerable oppression. The former answers itself, being a violation, without cause, of a faith solemnly pledged. The latter is another name only for revolution, about which there is no theoretic controversy.
A resort to violence is not a principled argument. If every disposition of a human populace is to be decided by violent conflict, then what need have we of arguments from principle? Let us just get to the killing and stop pretending we are reasonable.
Let us stop pretending the Union invasion was based on any noble idea. It wasn't. It was just a bigger group of people forcing their will on a smaller group of people. In that regard, it was based on the same underlying concept as slavery.