Who is Douglas Graham from On Killing and what is their importance?

Douglas Graham is a medic with the First Marine Division in Vietnam definitely noticed during his tour of duty how much members of the opposing teams could fire their weapons without anyone being hurt by the ammunition. People were killed and injured but clearly much of the shooting, like shouting, was for effect, to please superior officers, to posture, and because of the success of the squeeze-the-trigger training. In this sense, gun firing was, to use a sexual metaphor, like a great deal of male masturbation.