OK, would it have been better to say that his claim that "Prior to the American Civil War, it was popularly assumed that states which had freely chosen to enter the Union could just as freely withdraw from said union at their own discretion" is completely false?
The Republic was governed by law, not the masses. There was no admonition against secession, nor consequence of enforcement ever vested in the central government.
Nothing allowing it either.
The secession produced no negative circumstances until Lincoln’s call for troops and the ensuing invasion.
Your point about ‘nothing allowing...’ is moot.
[You] Nothing allowing it either.
Doesn't work like that, Bub -- and you know it. We've been over this, and you are now responsible for knowing it.
Powers not delegated are reserved. See Federalist 49 and 84.
It is evident, therefore, that, according to their primitive signification, [bills of rights] have no application to constitutions professedly founded upon the power of the people, and executed by their immediate representatives and servants. Here, in strictness, the people surrender nothing; and as they retain every thing they have no need of particular reservations.
-- Hamilton, Federalist 84