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
Leonidas I stood in higher regard, nor was Sparta less powerful in 478 BC than it had been in 481 BC. This selection of Leonidas to lead the defense of Greece against Xerxes' invasion led to Leonidas' death in the Battle of Thermopylae in 480 BC. Upon receiving a request from the confederated Greek forces to aid in defending Greece against the Persian invasion, Sparta consulted the Oracle at Delphi. The Oracle is said to have made the following prophecy in hexameter verse: In August 480 BC, Leonidas marched out of Sparta to meet Xerxes' army at Thermopylae with a small force