13 - The defence of Thermopylae (191 B.C.)

Summary

With the settlement of the eastern problem and the occupation of Coilē-Syria, Antiochus III was now free to turn his attention to the Aegean world. His operations in the area soon brought him in conflict with Rome. Diplomatic negotiations failed to achieve an agreement, and Antiochus, disheartened by the toughening of the Roman policy, yielded to the promises and enticements of the Aetolians, incited by the overthrow of the pro-Roman faction at Demetrias, to ‘liberate’ Greece and thereby possibly improve his bargaining position. Antiochus had at his disposal in Asia Minor only about 18,000 troops (see p. 18 above), but he crossed the Aegean hastily at the beginning of the winter hoping to receive support, especially from the Aetolians and Philip V. In the first months of his stay in Greece he engaged in an exhaustive diplomatic and military campaign to make sure of allies for the expected confrontation with the Romans. But the Roman invasion came too soon: 20,000 infantry, 2,000 cavalry, and 15 elephants crossed to Greece from Brundisium in the early spring (Livy 36.14.1; App. Syr. 15(65)). Antiochus was caught unprepared: the bulk of the army, especially the cavalry, was stranded in Asia; part of his landing force was scattered over Greece in garrisons, and a number of them surrendered to the Romans. Worse, the expected local help did not materialize: Philip V sided with Rome and the Aetolian auxiliary numbered only 4,000 infantry. At this stage Antiochus had 10,000 infantry, 500 cavalry, and six elephants of his own (Livy 36.15.3). In these circumstances he had to rule out a confrontation on the open field.