The Cambridge History of Warfare

From the reign of the emperor Diocletian (AD 285–305) until the development of firearms in the fourteenth century, the essentials of military organization, strategy, and tactics in Europe display a startling continuity. This reflects in part the enduring dominance of Roman military topography – the surviving infrastructure of fortified cities, fortresses, ports, and roads created in the third to fifth centuries. After the gradual dissolution of imperial power in the western half of the empire during the fifth century, those responsible for military decision-making in Rome's successor states had neither the inclination nor the resources to eliminate Roman walls. Like Byzantine emperors in the east, the Romano-German rulers differed little from the later Roman emperors in the means they used to control and make effective use of these assets. Continuity also reflects the unchallenged superiority of ancient military science, which decision-makers could find in books such as Vegetius’ Concerning Military Matters and the substantial contact between the West and Byzantium which stimulated the exchange and study of ancient military techniques.