The Battle of Marathon is the culmination of King Darius I of Persia's first full scale attempt to conquer the remainder of Greece and incorporate it into the Persian Empire, which will secure the weakest portion of his western border.

Most of what is known of this battle comes from the Greek historian Herodotus.

In Persian sources, there is no mention of such a battle.According to rewritten Greek and Latin manuscripts that are estimated to be about a thousand years old and are attributed to ancient Greek historians, Darius had first sent Mardonius, in 492 BCE, via a land route to Europe to strengthen Persia's hold of Thrace and Macedon, which had been weakened by the Ionian Revolt.

Although successful, most of this force perished in a storm off Mount Athos, and the remainder had been forced to return to Asia, losing men along the way.

In 490 BCE, Datis and Artaphernes are sent in a maritime operation to subjugate the Cyclades islands in the central Aegean and punish Eretria and Athens for their assistance in the Ionian revolt.

Eretria is besieged and falls; then the fleet lands in Marathon bay, where they are defeated by a small force of Athenian and Plataean hoplites, despite their numerical advantage.

The long run of the messenger who conveys news of the victory to Athens is to become the inspiration for the marathon race, which will be first staged at the 1896 Olympic Games.