Sherman wasn't a butcher, so much as a looter. And by the time Sherman was in charge and marchin' through Georgia, the South was falling apart and its armies disintegrating. Sherman's army looted GA because there was no rebel army to oppose it and make it concentrate on fighting.A couple of points.
1) The Southern economy was based on slavery at that time. Even the local store keeper who owned no slaves was part of and benefited from that economy.
2) As the war progressed, the Southerners were defending their families, homes and properties. If I had lived in the South at that time, I would also take up arms in defense of my family against a brutal invader. (General Sherman was a butcher.)
The CSA armies had pretty high desertion rates. While it's easy nowadays to whip up regional pride by telling the folks how the Rebs whipped the Blues, the South was a pretty big place. Many areas had few slaves and even those that had a significant slave presence rarely saw a Yankee, away from the railroads and river systems where the Yanks ran their supply routes. And yup, in the fertile plantation areas and the ports, the economy was dominated by cotton and the planter class. In the backwoods, you probably never saw a slave and lived off what you grew in the back 40. Your average Southerner was a subsistence farmer up to about 1950.
West VA seceded from the Confederacy because it didn't want to fight for rich planters and throughout other Appalachian areas, there was almost no support for the war. Contrary to popular belief, the hillbillies gave no shit about the Confederacy.