(June 22, 168 BC), decisive military engagement in the Roman victory over Macedonia in the Third Macedonian War. The Roman general Lucius Aemilius Paullus, by means of adroit tactical maneuvering, enticed the Macedonian king Perseus from his impregnable position on the Elpeus (Mavrólongos) River to occupy a weaker position in the plain south of Pydna (now Kítros, Greece; the actual site was probably near Kateríni).

During the battle the Macedonian phalanx, in a state of disorder after crossing broken ground, was penetrated by the Roman legionaries, whose short swords were more effective in close combat than were the Macedonian pikes. Perseus' left wing of Thracians and light troops was defeated by the Roman allies. Macedonian losses were great; Perseus fled, allowing the Romans to end the Macedonian monarchy and divide Macedonia into four republics.