If they had asserted their authority in an atmosphere when slavery had never been an issue, say for some very real economic shenanigans I read were being forced upon the south by the north, then I think the war would have taken a differet direction. The churches of the north got their moral dander up over slavery and the south would have never won that arguement. If the arguement had simply been about economics and deprivation of the south’s rights to conduct say cotton trade with the factory mills of Europe, the moral conscience of the Christians would never have gotten involved and the outcome would have been different. There might not have even been a national split but a final working out of a solution.
Longstreet was said to have stated” We should have freed the slaves first and then fired on Sumpter” He had grasped that the north would have had no moral imperative to continue the fight and that the powers of Europe would have been more disposed to render aid to the southern cause if slavery had not been the issue!
Longstreet never said that, Michael Shaara did. He put those words in Longstreet's mouth when he wrote his novel, "The Killer Angels".