In this study, the author uses the letters, diaries, memoirs, and reports of veterans from three conflicts - the First and Second World Wars and the Vietnam War - to establish a picture of the man-at-arms. She suggests that the structure of war encourages pleasure in killing, and that ordinary, gentle human beings in civilian life can become enthusiastic killers without becoming "brutalized" by the horrors of combat. She also contends that people find ways of creating meaning out of war, and that one way to do this is to find satisfaction in it, especially in the "primal" act of slaughtering an enemy that you can see and touch. She believes that violent and sadistic men are not the best killers, and that it is the men motivated by emotions like love and empathy that become the most lethal individuals on the battlefield. Bourke goes on to suggest that it is the feeling of guilt itself that may enable what soldiers believe to be legitimate killing, and presents evidence of the way in which combat could become atrocity in 20th century warfare.