The outcome of the Battle of Thermopylae, fought in 480 BC between an alliance of Greek city-states and the Persian Empire, was a Persian victory. A vastly outnumbered force of around 300 Spartans, led by King Leonidas, held the narrow pass against a much larger Persian army for three days. Their heroic stand became a symbol of bravery and sacrifice in the face of overwhelming odds. This battle delayed the Persian advance, allowing other Greek city-states to prepare for the subsequent battles, such as the naval Battle of Salamis, which eventually led to the defeat of Persia and a resurgence of Greek power.