DBWI: The US wins the War Between the States and remains united, but Prussia fails to bring the southern German states into the fold?

[World Mapping]

How about we reverse the fates of Germany and America:

What if the Union had decisively defeated Confederate forces at Antietam in September 1862 (maybe Order 191 gets lost or something), and eventually won the War Between the States, while Prussia failed to bring the South German States into the German Empire?

 

[AuH₂O]

World history would be changed drastically. The USA wouldn't have joined the Central Powers (if they even exist in this TL), and probably wouldn't have joined the Great War at all, if the Great War happens. Now, onto Prussia. We would probably see the establishment of a North Germany and a South Germany. That would create a pretty big rivalry, possibly leading to an alternate Great War that starts due to North and South Germany's rivalry. I'd imagine the alliances in this war would look something like this: North Germany, Russia, Italy, The Netherlands, and Sweden vs South Germany, France, Belgium, the UK, and the British Commonwealth.