A brief survey of the combat methods of the Hellenistic period will make it easier for the reader to follow the discussion on the fundamental questions arising from the analysis of the courses of the battles. We shall deal here only with the two largest armies, the Seleucid and the Ptolemaic, omitting the Antigonid army of Macedon, and also the small armies of the ‘ splinter’ states like Epirus, Pergamum, Pontus, Cappadocia, Armenia, etc. Although these armies included most of the components of the Seleucid and Ptolemaic armies, they differed from the latter in the number of the various types of units, in the ethnic origin of the soldiers and the way they were recruited, as well as in the total number of troops at their disposal, and consequently also in the way they operated on the battlefield. It must also be remembered that only the Seleucid and Ptolemaic armies utilized war elephants, which had more than a minor influence on the deployment of forces and the planning of a battle.

The sources of information available to us are varied. They include primarily several dozen battle descriptions in the literary-historiographic works covering the Hellenistic period. As far as the Seleucid and Ptolemaic armies are concerned, the campaigns of Antiochus III, recorded by Polybius, are the most illuminating. In addition to battle descriptions, we have a number of treatises on the theory and art of warfare outlining mainly the composition of the various tactical units and sometimes also their deployment and operation on the battlefield.