Wrong. As Article 1, Section 10 of the Constitution notes:
No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.
That clause contains no prohibition of State secession, a right the States (even those which did not explicitly reserve it, via their ratification documents) reserved by their insistence upon, and ratification of, the Tenth Amendment.
The right of secession was recognized at the time. As William Rawle (http://www.constitution.org/wr/rawle_32.htm) observed:
It depends on the state itself... whether it will continue a member of the Union. To deny this right would be inconsistent with the principle on which all our political systems are founded, which is, that the people have in all cases, a right to determine how they will be governed.
As Mr. Rawle noted, the foundation of our union is this:
THE PEOPLE HAVE IN ALL CASES, A RIGHT TO DETERMINE HOW THEY WILL BE GOVERNED.
As for your post, once a State had retired from the Union, it was no longer bound by Article 1, Section 10, or any other article of the Constitution.
Thanks for the reply...
And what if a state joined the confederacy and allowed the CSA army to occupy into its territory before formally ratifying its act of secession? Is Article 1, Sec. 10 meaningless as long as the state says, "Oh, I was going to secede but just hadn't made it official yet"?
No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.
But it does NOT say:
No State shall, UNLESS IT HAS SECEDED, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.
Unless one wants to rewrite the Constitution thusly, it contains a flat prohibition against states exercising authority. Rewriting the document is the liberals way, a trap we should avoid.
What about the 10th Amendment? It reserves to the states and people powers not prohibited to them by the Constitution, but Article 1, Section 10 flatly and plainly prohibits actions of state sovereignty.