Vegetius' late Roman text became a well known and highly respected 'classic' in the Middle Ages, transformed by its readers into the authority on the waging of war. Christopher Allmand analyses the medieval afterlife of the De Re Militari, tracing the growing interest in the text from the Carolingian world to the late Middle Ages, suggesting how the written word may have influenced the development of military practice in that period. While emphasising that success depended on a commander's ability to outwit the enemy with a carefully selected, well trained and disciplined army, the De Re Militari inspired other unexpected developments, such as that of the 'national' army, and helped create a context in which the role of the soldier assumed greater social and political importance. Allmand explores the significance of the text and the changes it brought for those who accepted the implications of its central messages. "Essential." Choice "The full story of Vegetius in the medieval era has not been told. Christopher Allmand … has perhaps capped his career with what is likely to be the definitive study of Vegetius in the Middle Ages for the foreseeable future." Everett L. Wheeler, Reviews in History "… [a] comprehensive survey of the surviving manuscripts … Very much a labour of love, Allmand’s survey is a valuable addition to our understanding of medieval mentalités." Nicholas Vincent, History "The De Re Militari of Vegetius is a valuable work and required reading for anyone interested in medieval military history." Bernard S. Bachrach, War in History This book explores the medieval legacy of Vegetius' late Roman text, transformed by its readers into the authority on war. Christopher Allmand is Emeritus Professor of Medieval History at the University of Liverpool. He has published widely on the history of war and medieval society, including The Hundred Years War: England and France at War c.1300–c.1450 (Cambridge University Press, 1988) and The New Cambridge Medieval History, Volume 7: c.1415–c.1500 (as editor, Cambridge University Press, 1998).