Hi,
My favorite books are:
Keith Armstrong and others, Courage After Fire. Great for families, troops and therapists.
Dave Grossman's books, On Killing and On Combat. He is a former Army Ranger, and teaches military. These books are not expensive and explain a lot about how people do not want to kill, and how difficult it is for most to have killed. In On Combat, he explains the physiological changes of what happens when a person is in a life/death situation, and - for example, why a Soldier may think he did nothing to help his buddies, but in fact he really did a lot.
Jonathan Shay's books - Odysseus in America and Achilles in Vietnam. These are a more difficult read, and he compares the experience of Odysseus to all soldiers. He is a great psychiatrist, and has advice on how the military could help lower combat stress. Works at Boston VA.
Barbara