Answer:
In war, you lose what made you a free person. you are forced to live and die, and there is not much different from you and the person next to you. Everyone wants to be seen as a hero, nobody wants to be seen as afraid. They carried shame because they did not want to be seen as weak. The men in vietnam, which is what this book is about, were oftentimes people who had been drafted. The only reason they did not dodge the draft was so that they could avoid embarassment, and according to O'brien, thats how it continued into war.