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) Aetolians all joined the defence - the old and women joining the fight. Realising that the Gallic sword was dangerous only at close quarters, the Aetolians resorted to skirmishing tactics. The Gauls destroyed Kallion, on the borders between Eurytania and Aetolia, committing horrible atrocities, but the resistance of the entire Aetolian population at the site Kokkalia, where also the elderly and the women and children fought, dealt a decisive blow to the Galatian threat. According to Pausanias, only half the number who had set out for Aetolia returned. Eventually Brennus found a way around the pass at Thermopylae but the