Persian Wars
War I
Wars between the Greeks and Persians lasted throughout the period of the Persian Achaemenid dynasty (549-330 BC), although the term Persian Wars refers more specifically to the wars of Persian kings Darius I and Xerxes I, which ended in 478 BC. Conflict began with the conquest of Lydia when Cyres the Great of Persia triumphed over Croesus at Sardis in 547. Cyrus then swept along the coast of the Aegean Sea, gaining control of the Ionian towns formerly subject to Lydia. Most of these towns revolted, however, and had to be subdued. The Persians then installed friendly tyrants, and peace was maintained until the reign (521-486) of Darius, when the Ionian towns again rebelled. Many of the tyrants were killed or expelled. Supporting the revolt, Athens sent a fleet in 499 to aid the rebels, but by 493 the uprising had been suppressed. In 490, Darius sent a fleet with an invasion force against Athens, but the Persian army was defeated in the Battle of Marathon.
War II
Darius's son and successor, Xerxes, determined to punish Athens, invaded Greece in 480. At first successful, the huge Achaemenid army, estimated at more than 100,000 troops, was delayed at Thermopylae by Leonidas and his Spartan forces. Finding a path to the rear of the Greeks, the Achaemenid army annihilated them and marched to Athens, whose citizens had fled to nearby islands. Although Athens was burned, the Greeks decisively defeated the Persian fleet at Salamis. Xerxes returned to Persia, leaving an army to subdue Greece. The following year, however, this army was defeated at Plataea, ending the danger of Persian invasion.
For the next 30 years the Greeks fought under Athenian leadership, winning back territory from the Persians in Thrace and Anatolia, although Greek intervention in Egypt ended in disaster. Enmity among the Greeks led to the Peloponnesian War (431-404) between Athens and Sparta, during which the Persians played one opponent against the other. In 411, Sparta made peace with the Persians and recognized Persia's claims to the Ionian towns. Clashes did not cease, however; the more comprehensive King's Peace was made in 387-386, leaving under Achaemenid rule only those Greek cities that were in Asia. This peace did not end Persian intrigues with or against various Greek city-states, and many Greek mercenaries served in Persian armies or navies. Only the conquests of Alexander the Great ended the Achaemenid Empire and the wars between Persia and Greece.
The Greek historian Herodotus provided the principal source of information on the conflicts in his History. Another ancient Greek, Xenophon, described an expedition (401) by Spartan mercenaries in the service of the Persians in his Anabasis.