Battle of Thermopylae
The Persian victory at Thermopylae opened southern Greece to Xerxes, thereby expanding the Persian empire. The battle is an example of heroism and persistence against seemingly overwhelming and impossible odds in that the Greek army consisted of roughly 7,000 soldiers in contrast to the 300,000 Persian. Regardless, the Greeks held their ground for two days while an even smaller Greek force held the Persians in place for another day, allowing the Greek army to evade total destruction. The confidence gained at Thermopylae propelled the Greeks to battlefield victories over Persia at Salamis and Plataea, reinforcing the prestige of Sparta and raising Greek morale in its long war against Persia.
While technically a military defeat for the Greeks, Thermopylae was a tactical and moral victory and the start of an impression and unexpected string of Greek victories over Persia. The pass at Thermopylae, in particular, was an ideally suited tactical situation for the style of warfare the Greeks sought. Using a hoplite phalanx to block the narrow pass, there was little risk the Persian cavalry could outflanking them. As such, it was impossible for the Persian infantry to assault the Greek phalanx with any real measurable results. By defending at Thermopylae allowed the Greeks maximized their forces in conjunction with the terrain available.
With Thermopylae being a place of great strategic importance because it commands the pass for any forces traveling south from Thessaly through Lokris and into Boeotia. Preventing Persia’s advance was the goal. Given the Greek army’s smaller numbers, taking the strategic defensive enabled Greece to avoid a costly decisive battle and allow them to live to fight another day and in a more advantageous setting.