What you quoted from the Declaration.. which is not the "law of the land", the Constitution is.... SUPPORTS the right of States to secede. It does NOT support the use of Federal troops to keep a State in the Union.
So again, my question has not been answered.
If you like, since you like South Carolina as the "legitimate" example, just show me where in the
Constitution the Federal Government was delegated the power to militarily force SC to remain in the Union.
BTW, SC did NOT have a "popular vote" to secede as you seem to imply. They held a convention and the people sent delegates. This is pretty much the same format that was used by all the Confederate States. An "Ordinance of Secession" was passed at a convention. I'm not aware of ANY of the Confederate States that subjected the Ordinances to a popular vote. Correct me if I am wrong.
Then the heroic day of December 20, 1860, came. The Convention adopted the Ordinance of Secession on roll call vote 169-0. At 7:00pm, the delegates signed the Ordinance of Secession declaring their political withdrawal from the United States. The State of South Carolina became the Commonwealth of South Carolina--the Palmetto Republic. During the next days, the Convention passed laws and resolutions a new nation would pass--South Carolina was a new nation.
[edit] Oh, and the idea that the loyal Union populations of the CS were being "held against their will" is totally destroyed by the fact of the armies of the CS. Unless you want to maintain that the CS armies were all drafted against their will and we're unenthusiastic fighters as a result.