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.