Hoffman Nickerson's work is dedicated to the history of wars during the era of the Roman Empire and the Middle Ages, that is, from 27 BC. e. until the end of the fifteenth century. Based on the results of modern research, the author gives a general picture of the wars, explains how and why they occurred, describes the strategy and tactics of military operations in the Crusades, analyzes in detail the reasons for the victories and defeats of the parties in the battles of Hastings, Muret, Bouvain, John's campaign Plantagenet, the battles of Crecy, Poitiers, etc., traces the history of the development of the army as a military organism. The book is equipped with maps and diagrams that give a more complete idea of the nature of the battles described.