The Persian Wars began in 499 BC with the revolt of Ionia. Ionia, a Greek polis, had been under Persian rule since 546 when Croesus' army was defeated by the Persian king Cyrus.

When the Ionians revolted against Persian rule in 499, the Athenian assembly voted to send military aid to Ionia. The Ionians were not successful in their revolt and were crushed entirely by Persian forces by 494. However, Darius, the king of Persia, was furious at the Athenians for aiding the rebel Ionians as Athens had already sworn allegiance to him. With this affront in mind, Darius attacked the Greeks in 490.

Darius fully intended to punish the Athenians for aiding the Ionians. He sent ships to Greece and his forces burned Eretria on the way to meet the Greek forces at Marathon. The Athenians, clearly out numbered by the Persians, sent to Sparta for aid, but received no response.

Lead by the Athenian general Miltiades, the hoplites of the Athenian army met the Persians on the plains of Marathon. Although they were out numbered, due to a carefully planned strategy, the Athenians were able to force the Persians into hand to hand combat, where the Athenians were superior. The Athenians were thus able to drive the Persians back and defeat them.

The Battle of Marathon was a benchmark in the history of Athens. For the men who fought there, it was a badge of honor. It also reaffirmed Athens commitment to democracy over totalitarianism. For Persia, it was a tremendous blow. Persia was the greatest empire in the world at that time. Their defeat by the Athenians was an insult and could not be forgotten.

Darius swore vengeance on the Greeks for his defeat at Marathon. However, before he could mount a full scale invasion, he died, leaving his son, Xerxes, as ruler of Persia. It would be Xerxes, then, who would lead the invasion of Greece and begin the last chapter of the Persian War.