Psychology of Killing

[Paddy™]

In conjunction with the above I also recommend "On Killing: The Psychological Cost of Learning to Kill in War and Society" by Lt. Col. Dave Grossman. Unfortunately he has some rather ridiculous beliefs about video games leading to high school massacres and the like, but apart from that it's worth checking out.

Fascinating topic. It's totally counter-intuitive to think of soldiers resisting killing so strenuously.