In 499 BC, the then-tyrant of Miletus, Aristagoras, embarked on an expedition to conquer the island of Naxos, with Persian support however, the expedition was a debacle and, pre-empting his dismissal, Aristagoras incited all of Hellenic Asia Minor into rebellion against the Persians. This was the beginning of the Ionian Revolt, which would last until 493 BC, progressively drawing more regions of Asia Minor into the conflict.
Seeking to secure his empire from further revolts and from the interference of the mainland Greeks, Darius embarked on a scheme to conquer Greece and to punish Athens and Eretria for burning Sardis. The first Persian invasion of Greece began in 492 BC, with the Persian general Mardonius conquering Thrace and Macedon before several mishaps forced an early end to the campaign. In 490 BC a second force was sent to Greece, this time across the Aegean Sea, under the command of Datis and Artaphernes.
The allied Greeks followed up their success by destroying the rest of the Persian fleet at the Battle of Mycale, before expelling Persian garrisons from Sestos (479 BC) and Byzantium (478 BC). The actions of the general Pausanias at the siege of Byzantium alienated many of the Greek states from the Spartans, and the anti-Persian alliance was therefore reconstituted around Athenian leadership, as the so-called Delian League.
The Persian war was remarkable not only for its ferocious battles, which showcased the superiority of Greek military methods, but also for the striking personalities involved, the democratic character of the military command, and