Hoffmann Nickerson's work is devoted to the history of wars in the era of the Roman Empire and the Middle Ages, that is, from 27 BC. e. until the end of the XV century. Based on the results of modern research, the author gives an overall picture of the wars, explains how and why they took place, describes the strategy and tactics of hostilities in the Crusades, analyzes in detail the reasons for the victories and defeats of the parties in the battles of Hastings, at Muret, at Bouvain, the campaign of John Plantagenet, the battles of Crescy, 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 picture of the nature of the battles described.