Even more narrowly, the Confederate aim was only for the benefit of SOME of the white folks, only the ones who owned slaves and had power and wealth. The poor folks were despised cannon fodder. The book "Bitterly Divided" by Professor David Williams shines the light on the Confederate war against their so-called "own people" both black and white.
This is disproven by your boy, Sherman:
Dear Brother:.....It is about time the North understood the truth. That the entire South, man, woman and child are against us, armed and determined. It will call for a million men for several years to put them down. They are more confident than ever, none seem to doubt their independence, but some hope to conquer the northwest. My opinion is there never can be peace and we must fight it out.