Read Turtledove’s “Southern Victory” series starting with “How Few Remain”. It’s a great alternate history series, which continues on I other series to explore the results of a Confederate victory all through the Civil, Spanish American, and Great war, among others.
I think he went too far with the Nazi parallels. Feathersone as Hitler. Blacks instead of Jews going to death camps. There was a lot he could have done without going down those roads.