In The Red Badge of Courage , how does Henry ("the youth") respond to his first experience of combat?

In The Red Badge of Courage, how does Henry (“the youth”) respond to his first experience of combat? How does this change when the Confederate Army launches their second attack against Henry’s position? What is the primary cause of this change in Henry?  Is he a coward? Does Crane provide an insight into the mind of a combat soldier, or is the novel simply for entertainment?