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 the Battle of Marathon in 490 BC. By 480 BC Xerxes had amassed a huge army and navy, and set out to conquer all of Greece. The Athenian politician and general Themistocles had proposed that the allied Greeks block the advance of the Persian army at the pass of Thermopylae, and simultaneously block the Persian navy at the Straits of Artemisium. A Greek force of approximately 7,000 men marched north to block the pass in the middle of 480 BC. The Persian army, alleged by the ancient sources to have numbered over one million, but today considered to have been