

Historian Michael Clanchy noted "the medieval axiom that laymen are illiterate and its converse that clergy are literate", so it may be the case that few soldiers read Vegetius' work. As archaeologist Robert Liddiard explains, " Pitched battles, particularly in the eleventh and twelfth centuries, were rare." Īlthough his work was widely reproduced, and over 200 copies, translations, and extracts survive today, the extent to which Vegetius affected the actual practice of warfare as opposed to its concept is unclear because of his habit of stating the obvious. One of the tenets he put forward was that a general should only engage in battle when he was sure of victory or had no other choice. According to Vegetius, infantry was the most important element of an army because it was cheap compared to cavalry and could be deployed on any terrain.

ĭe re militari was divided into five books: who should be a soldier and the skills they needed to learn, the composition and structure of an army, field tactics, how to conduct and withstand sieges, and the role of the navy. Though Vegetius had no military experience and De re militari was derived from the works of Cato and Frontinus, his books were the standard for military discourse in Western Europe from their production until the 16th century.

While Western Europe relied on a single text for the basis of its military knowledge, the Byzantine Empire in Southeastern Europe had a succession of military writers. Described by historian Walter Goffart as "the bible of warfare throughout the Middle Ages", De re militari was widely distributed through the Latin West. Publius Flavius Vegetius Renatus wrote De re militari (Concerning Military Matters) possibly in the late 4th century.

Vegetius, De re militari, preface to book 3.
