"Azulon knew that after Roku died, the next avatar would be from the Air Nomads. That's why they were attacked first."

Huh. I always thought of the Earth Kingdom like old timey Kievan Rus: a group of city-states ruled by "princes" that all were under the sway of the capitol — Kiev. Kiev's Prince was still a prince, but he was extra princey, for flavor.

5 Year Plan
I assumed when I watched the show the first time that, while the war was mostly a grind for the first 100 years*, Ozai had amped things up considerably when he came to power. And if I recall correctly, Zuko was around 11 when that happened. So, five years of occupation in the Earth towns is about right if…

Oh, God
Why hast thou forsaken me? I knew it was coming, but I hoped against hope that it wouldn't arrive.