How do Henry's attitudes toward the war and toward himself change during the course of the novel? Do the changes warrant the conclusion he reaches toward the end of the book?

Henry begins to look at courage and valour differently. He drops the youthful illusions of bravado and sees war for the hell it is. They are animals trying to survive. This relates directly to how he sees himself at the end of the book, a more war weary but self-aware young man.