Like the other Hellenistic armies, the Seleucid army on the battlefield was composed of phalangites, heavy cavalry, semi-heavy and light infantry, and at times also light cavalry and elephants. The backbone of the army, however, was the phalanx force of military settlers that was deployed in the centre of the battlefield and served as a sort of barbed and impenetrable porcupine which overran anything in its way as it advanced. It is rightly accepted that the eastern peoples had no proper answer to the massive power of the phalanx units, and that that deficiency enabled the Seleucids to control the complex variety of nations in the empire.

Polybius, the great historian of the period, consistently refers to the phalanx soldiers as ‘Macedonians’, and he does so even in his detailed description of the procession at Daphne in Judas Maccabaeus’ time (30.25.5). Many scholars, however, hold that in the course of time the Seleucid phalanx deteriorated from thè point of view of ethnic composition and operational ability. According to them, at the outset most of the military settlers making up the phalanx units were of Greco-Macedonian origin. But eventually they assimilated into the eastern environment through intermarriage with the local population, and when their offspring lost their military gifts, soldiers of indigenous Syrian origin joined the phalanx units (and perhaps also the settlements) and became a majority in them. The term ‘Macedonians’ applied to these units in the various sources thus denotes not national origin, but combat method, as it did in Ptolemaic Egypt.