OTL USG had a serious problem with what would today be known as clinical depression, from which he developed quite severe alcoholism - both of which progressively worsened throughout his life. During his time in the White House, he managed to remain very functional, and his presidency is not remembered for this. But what if, by some chance of chemistry, he becomes substantially more unstable and ends up practically unable to fulfill the duties of office? How would Reconstruction and American history as a whole change?