In 480 BC, Xerxes I, the king of Persia, was on a mission to expand his vast empire. He set out to invade Greece with a colossal army and a powerful navy. The Greeks formed a coalition of city-states under the leadership of Sparta, known for its formidable warriors. Motivated to protect their homeland, a Spartan king named Leonidas mustered a brave force of around 7,000 soldiers. To stop the Persian advance, Leonidas chose the narrow pass named Thermopylae. It lay between mountains and the sea, an ideal location for their inferior army. He planned to exploit the terrain to negate the Persian's overwhelming numbers, creating a chokepoint where a smaller force could hold off a much larger one, sacrificing a few to save many. The stage was set for the Battle of Thermopylae, a landmark event in world history.