Aetolian League
Building on anti-Roman sentiment in Greece, particularly among the city-states of the Aetolian League, Antiochus III led an army across the Hellespont planning to "liberate" it. Antiochus and the Aetolian league failed to gain the support of Philip V of Macedon and the Achaean League. The Romans responded to the invasion by sending an army to Greece which defeated Antiochus' army at Thermopylae.