Military writings regarding psychological reactions to combat tend to be confusing in that acute aspects of the disorder are not differentiated from chronic ones. In addition, documented precipitants, therapeutic interventions, and preventive measures are usually presented as if psychological reactions to combat were unitary. Upon review of much of the combat psychiatry literature, plus a selective review of stress studies in general, a case can be made for distinguishing acute from chronic psychological reactions to combat In so doing, precipitants, treatment, and preventive issues become more specific and helpful for each of these conditions. Finally, post-traumatic stress disorder may well differ in its character and course depending upon whether the stress was of an acute or chronic nature.