Man-stealers also cannot stand forever against the authority of God either. The wheels of God's justice may grind slowly, but they always grind exceedingly fine.
Yes, slavery is very evil. Thank you for pointing that out to us. Unfortunately for your argument, it happened to be Legal under Union rule in 1861.
Please take this into account in your future attempts to once again remind us how evil is slavery. That you feel the need to keep repeating the obvious makes you come across as a bit simple.