All the incidents subsequent to the appeal of Athens to Sparta are expressly referred by Herodotus to the interval between the sending of the heralds in 491 B.C. and the invasion of Datis and Artaphernes in 490 B.C. (cf.
His son, of the same name, was appointed (490), together with Datis, to take command of the expedition sent by Darius to punish Athens and Eretria for their share in the Ionian revolt.
It was in consequence of the aid which the people of Miletus lent to the Eretrians on this occasion that Eretria sent five ships to aid the Ionians in their revolt against the Persians (see IoNiA); and owing to this, that city was the first place in Greece proper to be attacked by Datis and Artaphernes in 490 B.C. It was utterly ruined on that occasion, and its inhabitants were transported to Persia.
But not only the expeditions of Mardonius (492) and Datis (490), but even the carefully prepared campaign of Xerxes, in conjunction with Carthage completely failed (48o479).
Inventio virium quibus corpora in Orbibus datis revolvi possint, facilior redditur et amplior.
Sparta had despatched an army in 490 to aid Athens in repelling the armament sent against it by Darius under the command of Datis and Artaphernes: but it arrived after the battle of Marathon had been fought and the issue of the conflict decided.