Conflicts that dominated the history of the eastern Mediterranean in the first half of the 5th century bc. In 499 bc the Greek cities of Ionia in Asia Minor revolted from the Persian empire. With some short-lived support from Athens and Eretria, they captured and burnt the important city of Sardis, but gradually the Persians regained control, the Greek fleet being finally crushed at Lade in 494. In 490 a Persian expeditionary force sailed across the Aegean. The capture of Eretria—the first goal—was achieved after a week-long siege and with help from Eretrian traitors. The Persians then landed in Attica but after a defeat at Marathon they were forced to withdraw to Persia.

In 480 a much larger invasion force threatened Greece, advancing along the northern and western shores of the Aegean. A small Greek army and a large Greek fleet were positioned respectively at Thermopylae and Artemisium, but despite vigorous fighting on land and sea the Greeks were forced to withdraw to the Isthmus of Corinth. With central Greece lost, the Athenians evacuated their city, while the Greek fleet, at Themistocles’ urging, lured the Persians into battle off Salamis. In these narrow waters the Greek warships had the advantage and won a decisive victory which caused the Persian king Xerxes to withdraw to Asia. Mardonius, his second-in-command, remained to continue the campaign with the army. In 479 Greeks and Persians met at Plataea. The Greeks were eventually successful, the Spartans and their Tegean allies ensuring victory when they overcame the élite Immortals (the Persian royal bodyguards) and killed Mardonius. Meanwhile a Greek fleet was winning another great victory off Mycale in Asia Minor. Soon afterwards some of the Greeks formed the Delian League to be the instrument by which they would continue the war against the Persians.