Commonly known as the Stand of the 300, Thermopylae was an amazing battle. The Persian Empire troops, let by Xerxes I, faced 300 Greek forces, led by the Spartans, led by Leonidas. Are you able to hold off the Persians? Are you able to defeat them before the flanking forces attack from the surrounding hills? Stand and become the object of legends? (480 BC) The Battle of Thermopylae was fought between the Achaemenid Persian Empire under Xerxes I and an alliance of Greek city-states led by Sparta under Leonidas I. The engagement at Thermopylae occurred simultaneously with the Battle of Artemisium: between July and September 480 BC. Lasting over the course of three days, it was one of the most prominent battles of both the second Persian invasion of Greece which, under Xerxes I was a delayed response to the failure of the first Persian invasion which had been initiated by Darius I and ended in 490VC by an Athenian-led Greek victory at the Battle of Marathon. Xerxes had amassed a massive land and naval force, and set out to conquer all of Greece. The Athenian politician and general Themistocles proposed that the allied Greeks block the advance of the Persian army at the pass of Thermopylae. Around the start of the invasion, a Greek force of approximately 7,000 men led by Leonidas marched morth to block the pass of Thermopylae against the Persian army, with between 120,000 and 300,000 soldiers. The outnumbered Greeks held them off for seven days (including three of direct battle) before their rear-guard was annihilated in one of history's most famous last stands. The Greeks blocked the only road by which the massive Persian army could traverse the narrow pass for two full days of battle.