Interesting historical perspective: Most people would say it was Lincoln with his Emancipation Proclamation, and Lincoln was a Republican. Technically speaking, that proclamation freed exactly zero slaves.

In the Confederate states, where Lincoln had no power to enforce it, no slaves were freed of course. Well, he just couldn't do it then but he had the noble idea, right? Nope.

In the border states that remained in the Union, the Proclamation continued slavery there because Lincoln desired to cooperation of those states. No slaves were freed where he could have enforced it.

So for anyone that was aware that Lincoln was generally a scumbag but were giving him credit for freeing slaves, you can go ahead and drop that exception.