The war was fought by the North to keep the South from seceding and to strengthen Northern control over the Southern states. The North, or Union, was fighting against the rights of states; it was fighting to destroy the agricultural way of life of the South so as forcibly to bring about the dominance of the industrial way of life of the North.
Consequently, Secession is a Constitutional Right of EVERY State, a Safeguard of Last Resort to unhinged Federal Tyranny (See Current State of Biden’s America for proof).
