I would argue that the Constitution is quite clear on where that particular power lies.
The Constitution, and the conventions it established, required the assent of 2/3 of the states to ratify it. Arguably, in order to break that covenant, the agreement of 2/3 of the states was also necessary. The 7 states that ultimately formed the confederacy did not even equal to 1/3 the total number at the time.
Are you willing to kill someone over those beliefs?
Are you willing to kill hundreds of thousands of people for those beliefs?