The South seceded from the Union as folks like Alexander Hamilton and John Jay, two of the authors of the Federalist Papers, agreed that they could do under the Constitution.
Actually, no they didn't. They did it the way they figured they could do it and defied the union to stop them.
Remember "the powers of government may be reassumed by the people whensoever it shall become necessary to their happiness"?
Sure I do, but the belief in the god-given right to rebellion carried with it a price. It was never meant as carte blanche to do whatever you feel like at any time or for any reason (or no reason at all). And it also carried with it the immutable law of consequence. If the fire-eaters were serious about peaceful separation they could have attempted it instead of the belligerent unilateral rebellion they tried.
Who knows - it might have worked out better for them as well>
[You]: Actually, no they didn't. They did it the way they figured they could do it and defied the union to stop them.
The Southern states generally elected representatives to secession conventions much as states did in ratifying the US Constitution. Several of the Southern states went further than that in submitting the question of secession directly to the voters of their states. That was only done by one state in the ratification of the US Constitution. In that instance ratification of the Constitution failed by a ten to one margin. The Constitution was later ratified in that state by a small convention.
Where in the Constitution was the Federal government, or for that matter, non-seceding states given the power to stop a state from withdrawing from the Union?
Apparently you know better what the Constitution means than those two ratifiers of the Constitution and authors of the Federalist Papers I cited above. How wonderful that we have you to explain it to us.