Nonsense. The North could have let the seven cotton states secede in peace. They chose instead to coerce the cotton states back into the Union thereby starting the war.The South, who started the war, declared it was all about slavery. The Union, reacting to a rebellion, didn't have any say as to what the war was "about."
You and I always disagree on this point, period. Go ahead, take the last word as I aways let you do.