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 (279 BC) Battle of Thermopylae (279 BC) The Battle of Thermopylae was fought in 279 BC between invading Gallic armies and a combined army of Greek Aetolians, Boeotians, Athenians, Phocians at Thermopylae. The Gauls under Brennus were victorious, and advanced further into the Greek peninsula where they attempted to sack Delphi but were completely defeated. Gallic groups, originating from the various La Tène chiefdoms, began a south-eastern movement into the Balkan peninsula from the 4th century BC. Although Gallic settlements were concentrated in the western half of the Carpathian basin, there were notable incursions, and settlements, within the Balkan peninsula itself. From