Everything changed for the first time in 492 BC, when the Persians became envious of Greek control of the Aegean Sea and enraged by Greek help in the Ionian revolt against their domain. The Greek city-states first united when the Persians launched an invasion of Greece under the rule of Darius I. The first of what would be known as the Greco-Persian Wars ended with the Athenian victory at Marathon in 490 BC The city-states became more closely allied with the second Persian invasion of 480 BC. The Athenians and Spartans led the defensive military movement against the Persian forces of Darius' son Xerxes I, again demonstrating their superiority through several more battles before passing on the offensive and eradicate Persian forces from Europe before the end of the Second Persian War in 479