What did the Confederate States of America do when faced with a possible secession movement? Lake all states, of course, it brutally suppressed it. The rebels in the legendary"Free State of Jones" in Mississippi (the subject of
a new book by Sally Jenkins and John Stauffer) may, or may not, have been secessionists in a formal sense but they were against the CSA.
Had Lincoln let a weak Gulf Coast CSA secede in 1861, sans Virginia, North Carolina, Tennesse, and Arkansas, it would have been extremely vulnerable to internal rebellions of this type both by dissident whites and slaves.