This essay describes the studies concerning the psychology of soldier carried out during the First World War by Father Agostino Gemelli, in his triple role of chap lain, doctor and director of the Psycho physiological laboratory of the High Command of the Italian Army. Gemelli helped to bring to light the many applicative aspects of Psychology, he traced with more precision new lines of research, strengthening the growing institutional and epistemological autonomy of the discipline with his researches on pilots and on hearing, with the determination of the psychology of the fighters who had wide application on the field and thanks to the investigations on a anthropological and sociological level, such as those relating to the war folklore. In its philosophical dimension, the psychology of soldier fuelled and supported the audacious renewal project promoted within the Catholic Church by the Neo Scholastic theology, whose current goal was to redefine the modern man’s existential dimension through a pedagogic and cultural approach .
Keywords: First World War, history of psychology, history of psychiatry, Agostino Gemelli, Neo Scholastic, psychology of the soldier