Well, as I see it the North went to war to preserve the Union and won. The South , or as you say ‘’the Southern Slave Power leadership’’ went to war to preserve slavery and lost everything.
It is difficult to exercise the mental gymnastics that it takes to see the distinctions between Johnny Reb, The South, The Confederacy, the Great military leaders who fought for the south. I am pretty sure that Johnny Reb wasn't picturing himself lording it over some Panamanian banana plantation after winning the War. Chances are "the South" merely wanted to maintain its status quo in situ. But those Slave Power Magnates who forced the issue of secession to reinforce their peculiar institution are a whole other matter. They envisioned an empire of cotton, sugar, tobacco, chocolate, stretching through Mexico and Central America, across the top of S. America and on to Cuba. And every inch of it slave territory.
There were layers upon layers that constituted "the South". It is why I can forever consider Lee, Jackson, Stuart as great and noble American heroes, while at the same time, abhorring the likes of Davis and Stephens (and that putrid assassin).