The Hundred Year War

When the Fire Nation attacked, young Avatar Aang did not go down without a fight. He gave many of his fellow Air Nomads time to escape and go into hiding.
Now, nearly a hundred years later, the war that was kicked off with the near eradication of the Air Nomads was still dragging on. The Avatar had been reborn and fallen more than once since Aang gave his life. Due to the war, it was never really clear who the Avatar was at the time. What happens when the Avatar reveals themselves as they fight for the victims of this war?