For Wealth and Glory - The Kings of Proster, #1

Prince Proster was the seventh child in the royal line. His older brother had several children. Overall, there was no chance of Proster ever becoming king. His father had tried to suggest priesthood when Proster was a boy, but it never fit right with Proster. Instead he took up a sword and became very good with it. He and several noblemen's sons would spar against each other until no one dared challenge any of them.
With the decline in the next kingdom, Proster decided to go to war with it. He father refused to start a war just so that his son could fight someone. So, Proster took his band of warriors and went to war. Now King Proster has a serious problem. He has everything and yet has nothing.