What is the theme in The Last Mission by Harry Mazer?

Coming of Age is a main theme in this story. At the beginning of the novel, Jack Raab is a fifteen-year-old boy who thinks it would be great to go kill Hitler for the atrocities he has committed against Jews. Jack looks at war as a sort of game, something that is strategic and fair, unaware of the darker side of war. Jack is homesick when he first gets into the Army, anxious to contact his parents even though he knows that he cannot. Jack wants to receive letters and to have someone to write to, but has no one he can send letter to because no one who knows him is aware that he is in the Army.