What is the theme in Flags of Our Fathers by James Bradley?

Heroes is a theme in the book. One of the most difficult things about his war experience for Jack Bradley to deal with appeared to be his being labeled a hero. In Jack's mind, the heroes were not the six other Marines who just happened by when a flag needed to be hoisted up on a make-shift flag pole. The real heroes, he told his son years later, were the fellows that did not make it home. These were the soldiers that gave their lives for their country and for the American way of life.