In 499 BC, Athens sent troops to aid the Ionian Greeks of Asia Minor, who were rebelling against the Persian Empire (see Ionian Revolt). That provoked two Persian invasions of Greece, both of which were repelled under the leadership of the soldier-statesmen Miltiades and Themistocles (see Persian Wars). In 490 the Athenians, led by Miltiades, prevented the first invasion of the Persians, guided by king Darius I, at the Battle of Marathon. In 480 the Persians returned under a new ruler, Xerxes I. The Hellenic League led by the Spartan King Leonidas led 7,000 men to hold the narrow passageway of Thermopylae against the 100,000–250,000 army of Xerxes, during which Leonidas and 300 other Spartan elites were killed. Simultaneously the Athenians led an indecisive naval battle off Artemisium. However, that delaying action was not enough to discourage the Persian advance, which soon marched through Boeotia, setting up Thebes as their base of operations, and entered southern Greece. That forced the Athenians to evacuate Athens, which was taken by the Persians, and seek the protection of their fleet. Subsequently, the Athenians and their allies, led by Themistocles, defeated the Persian navy at sea in the Battle of Salamis. Xerxes had built himself a throne on the coast in order to see the Greeks defeated. Instead, the Persians were routed. Sparta's hegemony was passing to Athens, and it was Athens that took the war to Asia Minor. The victories enabled it to bring most of the Aegean and many other parts of Greece together in the Delian League, an Athenian-dominated alliance.