What is the main conflict in The Last Mission by Harry Mazer?

The Last Mission is a novel by the author Harry Mazer. This novel is about Jack Raab, a fifteen-year-old boy who lies about his age in order to enlist in the Army during World War II. Jack wants to represent his family in the fight against Hitler. However, Jack underestimates how difficult being away from home will be as well as the dangers of fighting a war, even from the air.