Battle of Magnesia

Battle context

The Battle of Magnesia was the decisive engagement of the Roman–Seleucid War, pitting a Roman and Pergamene force of roughly 30,000 against a Seleucid army more than twice its size at approximately 72,000. The scale of the Seleucid defeat was severe: Roman and allied casualties stood at around 5,000, while Seleucid losses reached some 53,000. The disparity in casualties effectively destroyed Antiochus III's capacity to contest Roman power in Asia Minor. The battle confirmed Roman military dominance east of the Aegean and ended Seleucid ambitions in the region, with Antiochus compelled to negotiate on Roman terms. Eumenes II of Pergamum, whose kingdom fought alongside Rome, emerged as a principal beneficiary, reinforcing Pergamene influence in western Anatolia. The engagement stands as a turning point in the Roman–Seleucid War, after which Antiochus III could no longer sustain offensive operations or challenge the Roman-led order taking shape across the eastern Mediterranean.