He passed the emancipation proclamation. Imbeciles have attempted to argue that this is not freeing the slaves at all because it only applied to rebellious territory and not free states. But,
1. The vast majority of slaves were in rebellious territory
2. Despite claims that the proclamation would have no effect due to only applying to the Confederacy (durr the Union didn't control dat durr!!!), the Union did in fact come to control vast swaths of Confederate territory, where this act would clearly be enforced by the military governors stationed therein, and once the Union controlled everything - obviously, it would be done
3. It's not clear that the executive branch would have the constitutional authority to use wartime powers to (more or less) rule by decree in non-rebellious areas, certainly the kinds of sanctimonious "states right's" activists who make this "Lincoln ain't freed no slaves!" argument would be offended had he actually tried to use expansive wartime powers in states that weren't warzones
Just more butthurt southern Confederate apologists. Your heritage is hatred, people who are proud of their Confederate heritage sicken me.