Sorry I’m. Going to reveal that I never finished a single path of hopes (I got soooo bored) and seeing everyone here talk about it is giving me an aneurysm. What do you mean they fire bombed Claude’s character. Edelgard is possessed? Hopes wtf are you doing. Houses is the only lore as far as I’m concerned what is this hot fresh bullshit
Claude decides to forge an alliance with the empire after being invaded by them a few months ago, declaring that their biggest enemy now is Rhea.. despite Rhea only showing up like two times before this.
He says it's okay to invade the Kingdom because they weren't so nice to them some centuries ago. It's also implied he leaked info to make Sreng invade as well. Double whammy.
So he invades Faerghus and fucks shit up, gets Margrave Gautier killed and eventually gets to Fhirdiad. He backtracks after TWISTD does a plot thing in the Federation (because it's no longer the alliance, he's king now). Then he goes to defend Edelgard at Garreg Mach, even though letting her down would mean her death and thus no war (which is pointed out to them). THEN he blitzes Rhea and headshots her with Failnaught while she's the Immaculate One. Yeah, that will definitely end the war!
Fun fact! Shez can even tell Claude that this will NOT end anything because Edelgard is out for conquest. Claude goes "that sucks" and continues with his plan anyway.
Edelgard gets turned into the Hegemon at the end of the first act in Azure Gleam. We find out pretty quickly that it mentally regressed her to when she was a kid. Now she's just a useless puppet who looks sad. Why did Thales not do this in Three Houses? Who knows!