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
Hydarnes II Hydarnes II Hydarnes II (, Old Persian: Vidarna), son of Hydarnes, was a Persian commander of the Achaemenid Empire in the 5th century BC. His father was one of the seven conspirators against Gaumata. During the reign of Xerxes I, Hydarnes was one of the commanders for the Second Persian invasion of Greece in 480 BC. He was appointed as the leader of the 10,000-man contingent of "Immortals", while his brother Sisamnes commanded the levy of the Aryans. On the first day of the Battle of Thermopylae, Hydarnes led the Immortals against the phalanx of Spartans under Leonidas I, but