What Is the Situation Constitutionally in a Civil War?

In the nineteenth century, following the civil war and during the civil war, they were primarily calling this the war of the rebellion, not a civil war. They remain in the union, but the people in them who are claiming to be part of the confederacy are in rebellion. And so too, becomes a period of constitutional creativity, where these folks are seriously trying to abide by the constitution, but aren't entirely sure about what to do.