Some other fantasy lands might have room for cowardly lions, but not Narnia. Prince Caspian defines its characters by the courage they possess. Whether they stand up or sit down, these heroes will fight, fight, fight. Even the heroes who don't wield a blade display courage—remember Lucy's courage to believe she saw Aslan when none of the others did? The villains are also defined by their courage, or rather, lack thereof. Miraz is a warrior, but he confuses courage with the willingness to fight. And the lords Glozelle and Sopespian stab a guy in the back, so 'nuff said, right? Point is: every character has some type of relationship with the ideal of courage, making it a super-ultra-mega important theme.
Courage is not about what the characters do in Prince Caspian. It's about why they do it.
No one is taught courage in Prince Caspian. You either are or you aren't.