Secession does not mean war, it only means the state(s) is leaving the Union. War comes from the fascists who cannot let the departing state(s) go in peace. The violence of the Civil War came from the Unionists who forced the 11 states back into the Union at gunpoint.
11 states? Not 13? What about the “secession ordinances” of Kentucky and Missouri? Why don’t you count those states as having seceded?
Your slave-holding heroes fired the first shot, pal.
The violence came because the seven states that had seceded thought that if it came to war, some of the slave-owning states that had not seceded might join them.
They had the choice, between peacefully seceding as a Confederacy of seven states, or starting a war and perhaps becoming a Confederacy of eleven or thirteen states.
They chose war.