History: American Civil War (1861-1865)

Secondly the South argued that each state had the right to secede—leave the Union—at any time, that the Constitution was a "compact" or agreement among the states. Northerners (including President Buchanan) rejected that notion as opposed to the will of the Founding Fathers who said they were setting up a "perpetual union". Historian James McPherson writes concerning states' rights and other non-slavery explanations:
While one or more of these interpretations remain popular among the Sons of Confederate Veterans and other Southern heritage groups, few professional historians now subscribe to them. Of all these interpretations, the state's-rights argument is perhaps the weakest. It fails to ask the question, state's rights for what purpose? State's rights, or sovereignty, was always more a means than an end, an instrument to achieve a certain goal more than a principle.