Expansion of Macedonia under Philip II a significant problem, blocking the main route into Greece. However, a second route into central Greece was available. In 480 BC, during the Battle of Thermopylae, the Persian king Xerxes had sent his army via a mountain track (the "Anopea") to outflank the pass. From this track, on the western side of Mount Kallidromon, another road led off and descended in Phocis. In 480 BC, a thousand Phocian troops were stationed above Thermopylae to guard the road and prevent a Persian assault on Phocis (though they notably failed to prevent the Persians using "Anopea"). However, in 339 BC, the Greeks
Battle of Thermopylae (191 BC) only the Aetolian League actually joined forces with Antiochus; other states either remained neutral or sided with the Romans. Antiochus managed to capture some cities in Greece, but was unable to obtain reinforcements from Asia before in 191 BC a large Roman army under the consul Manius Acilius Glabrio crossed from Italy and advanced on his position. Knowing he was outnumbered around 2:1 by the approaching Roman army, Antiochus hoped to use the narrow pass at Thermopylae to his advantage, taking inspiration from the earlier Greek city-states' stand against the much larger Persian army at the Battle of Thermopylae (480