The Persians sent a much larger force to conquer Greece. By this time, Athens persuaded the other city states to join in the fight.The Persians landed in northern Greece. A small Spartan force guarded the narrow mountain pass at Thermopylae. Led by the great warrior- king Leonidas, the Spartans held out against the enormous Persian force, but was defeated. The Persians burned Athens, but the city was empty. The Athenians lured the Persian navy into a narrow strait called Salamis. Then the Athenian warships drove into the Persian boats with underwater battering rams sinking the Persian ships. The next year, the Greeks defeated the Persians on land in Asia Minor. The victory marked the end of the Persian invasions.