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 illustrate this point. Militarily, although the battle was actually not decisive in the context of the Persian invasion, Thermopylae is of some significance on the basis of the first two days of fighting. The performance of the defenders is used as an example of the advantages of training, equipment, and good use of terrain as force multipliers. There are several monuments around the battlefield of Thermopylae. A well-known epigram, usually attributed to Simonides, was engraved as an epitaph on a commemorative stone placed on top of the burial mound of the Spartans at Thermopylae. It is also the hill on