I really thought Harry Turtledove’s 11 book epic series from 1890s through circa 1945 was brilliant. Ok too many characters.
He wrote the series based on the premise Lincoln surrendered. Turtledove who is a historian wrote three wars would occur and slavery would continue. War of 1890s, WW1 and WW2 He went further then that. He wrote that for the Confederacy there would be a point where the government decides A Final Solution for African Americans. The Holocaust happens here. Turtledove argues that if the US split back then this would have been inevitable.
Racism and the fundamental belief in White Supremecy would drive everything in the South so when the government enacts it the soldiers in the camp don’t have a hard time doing it. That the Adolph Hitler type leader would be a certainty for the South.
There were few good white people in the south in this series. One really a restaurant owner who was a Schindler type person who appeared in last few books.
Turtledove had his issues like dealing with Utah. I think that would have resolved decades earlier. Also Canada. I am not sure the North ever would have invaded Canada even though they were not allies with England.
If Confederate series shows everything would be not bad if there was a spilt folks ie southern idiots will use it to say “see it would not have been bad”.