Well to give you some hints, it requires you to find out why the war happened to begin with. States don't exactly declare war for no reason at all, after all. And it would require fixing that issue.
As a hint on how to fix it, it involves understanding that Elaia's past has consequences to the present and a willingness to do what is good even if it's going to be treasonous.
Okay, go the Historian Route when you do your attempt to heal the South. Jo knows how to pull it off in a way that doesn't tip off anyone about the fact that artifacts got stolen until it is too late. It also helps with Sussie's issues so you won't have to worry about her causing an incident. You can still go South if you want, but you can definitely return home in this version.