The first Persian invasion of Greece, during the Greco-Persian Wars, began in 492 BC, and ended with the decisive Athenian victory at the Battle of Marathon in 490 BC. The invasion, consisting of two distinct campaigns, was ordered by the Persian king Darius the Great primarily in order to punish the city-states of Athens and Eretria. These cities had supported the cities of Ionia during their revolt against Persian rule, thus incurring the wrath of Darius. Darius also saw the opportunity to extend his empire into Europe, and to secure its western frontier.

The Greco-Persian Wars were a series of conflicts between the Achaemenid Empire and Greek city-states that started in 499 BC and lasted until 449 BC. The collision between the fractious political world of the Greeks and the enormous empire of the Persians began when Cyrus the Great conquered the Greek-inhabited region of Ionia in 547 BC. Struggling to control the independent-minded cities of Ionia, the Persians appointed tyrants to rule each of them. This would prove to be the source of much trouble for the Greeks and Persians alike.