War is hell, but it can be a job–a strange job in which one voluntarily (these days) exposes oneself to the risk of physical and psychiatric injury. Our generation think we discovered post-traumatic stress disorder, but it is neither new, nor the commonest, mental health problem in the UK Armed Forces. That ‘honour’ goes to depression and alcohol. Are these always the result of going to war? No, things are rarely that simple. Can we treat them? Sometimes–but what makes people good soldiers makes them bad patients. Can we prevent them? Possibly–but only if we don't send people to war.