This study has presented a comprehensive overview of the origins of modern British and American military psychiatry, chiefly in response to World War I shell shock. The study examined the state of British psychiatry during the nineteenth century, as the new railroads, mines, and factories produced accident victims with post-traumatic stress disorders. As World War I began, psychoanalysis was in its infancy, and most British psychiatrists faced with a victim of shell shock fell back on an eclectic mix of treatments, including electro-shock therapy, hot baths, massages, moral persuasion, lectures, exhortation, etc. While a few British and American psychiatrists practiced either psychotherapy or disciplinary methods exclusively, the majority of practitioners used a variety of methods, depending on the doctor's point of view and the circumstances of the case at, hand. Psychotherapeutic developments in the inter-war period are also explored and discussed.