What is the theme in Sharpe's Tiger by Bernard Cornwell?

Courage is a central theme in this story. Richard Sharpe is the hero of this story, and as such he must display an extraordinary amount of courage. His rough childhood has prepared him to become a good fighting soldier, much more so than Lieutenant Lawford who grew up in a wealthy family. However, Sergeant Hakeswill also has led a rough life and shows no courage at all. This contrast shows that courage is not so much learned as inherited, at least in this story. A mystery remains who Sharpe's parents really are since he was born to a prostitute who abandoned him shortly thereafter. This novel does not explore the idea, but a subsequent Sharpe novel might. If so, it would make sense that Sharpe's parents are courageous as well.