Even though The main argument is why are the the kingdoms fighting and what are the kingdoms fighting about. There is a kingdom attacking a different kingdom. Because the Castle has a better advantage because the walls make a protection for the people in the castle and I know this because there are different people shoot different things at them.
The kingdoms are probably fighting because of land or, they stole something from the other kingdom. Also they might be fighting because of some other stuff like power and riches. Also the kingdom that is attacking is firing fireballs to burn the castle down.
The castle that is trying to defend the castle is doing a poor job of doing it because they are just letting the people