What is the theme in What It Is Like to Go to War by Karl Marlantes?

The main theme is fear and pride. Marlantes admits to feelings proud of his service in Vietnam, even though he looks back in sadness at some of the things he did. His own pride and that which he felt for his unit and the Marine Corps in general led him to take risks with his own and others' lives. This pride turned to shame upon returning home to the United States where the Vietnam war had been controversial. He was avoided by some and confronted by others because of his role. Treated like an outcast, he bean to think that he had done something wrong.