SummaryThe relationship between combat and psychiatric breakdown has been well recognised for decades. The change to smaller, professional armed forces has reduced the risk of large-scale acute psychiatric casualties, and should have led to a corresponding decrease in long-term ill health, but this expected reduction seems not to have happened. Likewise, attempts at preventing psychiatric injury, by screening before deployment or debriefing after, have been disappointing. Three reasons for this are proposed: a rethinking of the relationship between trauma and long-term outcome, catalysed by the attempts of US society to come to terms with the Vietnam conflict; a broadening of the scope of psychiatric injury as it moved to the civilian sector; and the increased prominence of unexplained syndromes and contested diagnoses such as Gulf War syndrome. Traditional psychiatric injury is predictable, proportionate and can, in theory, be managed. These newer forms of injury are in contrast unanticipated, paradoxical, ill understood and hard to manage. Traditional approaches to risk management by reducing exposure have not been successful, and may increase risk aversion and reduce resilience. However, the experiences of civilians in wartime or the military show that people are not intrinsically risk-averse, provided they can see purpose in accepting risk.