The US arms shipments to Britain, and later after the gun runner ship Lustiana, hoping to use its civilian passengers as a shield in breach of the rules of war, led to American popular support for joining with the Allies, which they eventually did to push Germany to defeat despite the newly Sovietised Russia withdrawing.
And it might be that Dixieland and Yankeeland would support the Allies and Axis, and WWI would have had an American theatre, too opening in 1915 or so. And any major war fought in North America in the 20th century would totally alter the form US neo imperial power and hegemony took, if any at all, in the latter part of the 20th century.
As a minimum, a different US would alter how Versaille and Balfour treaties were made and what who agreed to.
I didn’t like the first series, and would’ve quit it at episode 3 or so but I ended up without internet access for a couple of days and the whole series downloaded… It got better.
But yeah, life’s too short for TV shows that take time to be taken on faith. And if you did finish the first series and still not like it, more power to you.