Carefully analyzing the primary sources and works of other researchers containing descriptions of the most outstanding military events of ancient Greece and ancient Rome, prof. G. Delbrück draws conclusions about the state of military art in this era. The preface of Comrade Bocharov helps the Soviet reader to critically understand the general concept and individual conclusions of G. Delbrück. The first volume of Delbrück's work begins with a description of the Greco-Persian wars of the 5th century. BC e. and ends with Julius Caesar