The book is devoted to the study of the socio-political and military-ethical traditions of the Roman imperial army (1st century BC - 3rd century AD). These traditions interpret the contradictory unity of the ancient polis-republican institutions and the realities of the professional army, which is a kind of corporate community, a special social organism and a subject of political history. The author focuses on the specifics of the Roman military ethos, based on special behavioral stereotypes and values. Based on a wide range of literary and documentary sources, the moral, psychological, axiological and practical significance of the traditions of military camaraderie and discipline is considered, ideas related to the socio-political and moral qualities of soldiers, military valor, honor and glory, insignia and military career are analyzed, revealed the relationship between the Roman military ethos and army religion. The mechanisms and forms of participation of the army in political processes, the relationship between the emperor and the army are also studied.