The Battle of Marathon took place in 490 BC during the first Persian invasion of Greece. It was fought between the citizens of Athens, aided by Plataea, and a Persian force commanded by Datis and Artaphernes. The battle was the culmination of the first attempt by Persia, under King Darius I, to subjugate Greece. The Greek army inflicted a crushing defeat on the more numerous Persians, marking a turning point in the Greco-Persian Wars.
The first Persian invasion was a response to Athenian involvement in the Ionian Revolt, when Athens and Eretria sent a force to support the cities of Ionia in their attempt to overthrow Persian rule. The Athenians and Eretrians had succeeded in capturing and burning Sardis, but they were then forced to retreat with heavy losses. In response to this raid, Darius swore to burn down Athens and Eretria. According to Herodotus, Darius had his bow brought to him and then shot an arrow "upwards towards heaven", saying as he did so: "Zeus, that it may be granted me to take vengeance upon the Athenians!" Herodotus further writes that Darius charged one of his servants to say "Master, remember the Athenians" three times before dinner each day.
At the time of the battle, Sparta and Athens were the two largest city-states in Greece. Once the Ionian revolt was finally crushed by the Persian victory at the Battle of Lade in 494 BC, Darius began plans to subjugate Greece. In 490 BC, he sent a naval task force under Datis and Artaphernes across the Aegean, to subjugate the Cyclades, and then to make punitive attacks on Athens and Eretria. Reaching Euboea in mid-summer after a successful campaign in the Aegean, the Persians proceeded to besiege and capture Eretria. The Persian force then sailed for Attica, landing in the bay near the town of Marathon. The Athenians, joined by a small force from Plataea, marched to Marathon, and succeeded in blocking the two exits from the plain of Marathon. The Athenians also sent a message to the Spartans asking for support.