Kingdom of Red and Kingdom of Orange may have been allies in the war but after the war, Kingdom of Orange and Kingdom of Red took parts of the High mountains from the defeated nation of Republic of Blue. Kingdom of Red wants the High Mountains for it's resources and great defense. Kingdom of Orange didn't getting some of the High Mountains, they want all of it for defensive and they want resources to fix their broken economy. They can't agree and eventuallly go to war. Princess Celestia refuse to give aid to either countries.