There were two modes by which Greece might be approached from Asia. Bridges of boats could be thrown across the Bosphorus or the Hellespont, mere salt rivers, scarcely more formidable than the streams of the Euphrates and the Tigris. In this way Europe could be invaded in force, and the army sent across the straits, could pursue its way along the shore till it reached the rich plains of Thessaly, and from Thessaly passed into Boetia, Attica, and the Peloponnese. Or a fleet, with a land force on board, might proceed from Asia Minor across the Ægean, where the numerous islands, scattered at short intervals, seemed to have been arranged by nature as stepping-stones, whereby the adventurous denizens of either continent might cross easily into the other; and a landing might be suddenly effected near the very heart of Greece without a tenth part of the trouble that must be taken if the other line of route were pursued. In either case the attendance of a fleet would be necessary. If the more circuitous route were pursued, a powerful squadron must attend the march of the army along the shore, to convey its supplies; if the direct route were preferred, a still larger fleet would be necessary for the conveyance, not only of the supplies, but of the army itself. Darius gave a trial to each of the two plans. In the year B.C. 492 he sent a fleet and army under Mardonius by way of the Hellespont and the European coast; but this expedition met with severe disasters, the fleet being shattered by a storm off Mount Athos, and the land force greatly damaged by a night attack on the part of the Thracians.[14291] Two years later he dispatched the famous expedition under Datis and Artaphernes, which took its course through the islands, and landed perhaps 200,000 men on the plain of Marathon,[14292] but being there defeated by Miltiades, returned hastily to Asia by the sea route. The fleets employed on both these occasions were numerous,[14293] and appear to have been collected from several of the Persian maritime states;[14294] the proportion which the several contingents bore one to another is not stated, but there can be little doubt that the Phoenicians contributed the greater number. We have no details of the conduct of the Phoenicians on either occasion, beyond a casual notice that in the expedition of Datis and Artaphernes one of their vessels plundered the temple of Delium on the Boeotian coast opposite Chalcis, carrying off from it an image of Apollo plated with gold.[14295] The superstition of Datis deprived them of this valuable booty; but we may safely conclude from the anecdote that, while rendering service to Persia, the keen-witted mariners took care not to neglect their own material interests.