[BroJoeK]

Boogieman: "Before that, everyone properly understood that, if the individual states were not themselves sovereign, then they never would have had any power to form the “United States” in the first place."

I think most people "get" that you guys wish to endlessly debate your "theory of secession", and some even understand that your "theory" is false, because our Founders originally intended that secession must not come "at pleasure" but only from mutual consent or, in effect, a serious breach of compact.
And neither condition existed in December 1860.

But what only a few seem to grasp is that this "debate" is utterly irrelevant -- because Deep South declarations of secession did not cause Civil War.
Neither did forming a new Confederacy cause Civil War.
And neither did dozens of Confederate provocations in seizing Federal forts, ships, arsenals and mints.

What started Civil War was the Confederate military assault on Federal troops in Federal Fort Sumter, followed by their formal declaration of war against the United States, and sending military aid to pro-Confederates in Union Missouri.

In his First Inaugural Address (March 4, 1861) Lincoln announced to the Confederacy that they could not have a war unless they themselves started it.
So Jefferson Davis immediately ordered preparations for the assault on Fort Sumter.

Your arguments over secession theory are irrelevant to actual history.

[jeffersondem]

“What started Civil War was the Confederate military assault on Federal troops in Federal Fort Sumter . . “

This is also known as the Gulf of Tonkin incident, err, I mean the Fort Sumter incident.