[BroJoeK]

DiogenesLamp: "Beyond that, the Declaration of Independence says explicitly that people have a right to leave."

No actual Founder -- not one -- ever declared that states were free to secede "at pleasure".
All insisted or implied that one or both of two conditions must exist:

1. Mutual consent -- meaning the approval of Congress, or,

2. Oppression or usurpations -- meaning a material breach of compact, in Madison's words, "having the same effect".

Neither condition existed in December 1860, and so by our Founders' original intent, Deep South declarations of secession were illegitimate.

Still, that did not start the Civil War.
War only began after the Confederacy provoked, started & declared war, while sending military aid to pro-Confederates in Missouri.

[DiogenesLamp]

All insisted or implied that one or both of two conditions must exist:

Mutual consent -- meaning the approval of Congress, or,

That is factually wrong on the face of it. We received no "mutual consent" from the British, so stop wasting my time with bullsh*t.

Neither condition existed in December 1860, and so by our Founders' original intent, Deep South declarations of secession were illegitimate.

Excuse me, but I happen to have read the Declaration of Independence. Here's a copy so you can read it too. There are no such "Conditions" mentioned in that document. It says the exact opposite.