The southern economy before the civil war was cotton based. The cotton industry was based on slave labor. Take away slavery and the southern economy would collapse.
Why? Would all the blacks simply vanish? The fact is that most blacks stayed near their homes, becoming paid farm laborers or sharecroppers. By 1870, I believe, cotton production was back to pre-war levels. The reason it didn't help the south much was that the price of cotton had collapsed, with Indian and Egyptian cotton coming into the world market.
What would be threatened was the capital that the south had tied up in slaves, an asset second only to land in total value.
According to Slavery Inc's William Miles, "Many of the highest, manliest and most admirable qualities in the Southern character have been preserved in their pristine strength, if not engendered by our peculiar social and domestic system,".
Miles was among the most vehement supporters of slavery, arguing that it was a cornerstone of Southern culture. A few years before the war, he wrote in a Charleston, S.C., newspaper that black people were "debased, sensual, groveling creatures, hardly worthy of the name of men." Slavery, Miles wrote, was an institution created by God.
One of the most fanatical pro-slavers was the mentally unstable Confederate "fire eater" Edmund Ruffin.
With rapid collapse of Confederate forces in 1865, Ruffin proclaimed "unmitigated hatred to Yankee rule," and on June 17th, 1865, committed suicide.
We need to recall today's neo-confederate Big Lie, "slavery had nothing to do" with the Civil War....and there is a rather large bridge for sale in Brooklyn :)