Your logic escapes me.You are a slave owner per your own logic.
If it was me I'd have let them go and ensure the North took the West and bottled up the South where they were. Today the North would be a major power in the world and the South would be the Western Hemisphere's South Africa. IMHO the North did the South a favor they didn't deserve.The war was an aggression by the north. You need to blame them for the carnage.