It might have been supposed that the large naval and military force which must have been present in Western Asia during the last year of the revolt, would have been sufficient for the operations in Europe; but, apart from the inevitable losses in the war, a large number of the available troops may have been required for the occupation of the recently conquered districts. ◆H. vi. 43.◆ Be that as it may, very large reinforcements came westward from Susa in the spring of the year 492, under the command of Mardonios, that general who was destined thirteen years later to meet his death on the field of Platæa. He superseded Harpagos, Otanes, and the other unnamed generals in the command, so Herodotus says. It is, on the whole, unlikely that they were actually dismissed from their positions. The truth may be that Mardonios appeared as commander-in-chief. After arriving in Cilicia, he went on board the fleet, and sailed to Ionia along the coast, while his army marched overland. His first reported act on arrival in Ionia is the deposition of “all” the Ionian tyrants, and the establishment of democracies in the cities. Herodotus adduces this as a proof of the credibility of a story of his that, after the assassination of the pseudo-Smerdis, a proposal was actually made by Otanes, one of the conspirators, that Persia should be constituted as a democracy. That democracies were established in “all” the states is not the case. There were certainly exceptions, as the evidence of Herodotus himself indicates.[53] But that the measure was a wide one is shown by the great rarity of the instances in which any such tyrants appear in subsequent history, compared with the prominence of the part played by them in previous times. This measure seems to have been carried out by direct commission from Darius.[54] #POLICY OF DARIUS.# The severity meted out to the cities immediately on the suppression of the revolt is so strikingly in contrast with the consideration shown them in the years immediately following it, that it suggests the suspicion that the two modes of treatment were the outcome of two policies, one of which was that of the satraps and commanders in the West, and the other that of Darius himself. The reversal of policy shown in the settlement of Ionia by Artaphernes makes it appear as if the great satrap were acting under orders from Susa; and the further measures taken upon Mardonios’ arrival on the coast are certainly carried out in consequence of the instructions he had received.[55] The nature of the measures taken indicates some of the causes of unrest in the Greek cities previous to the revolt; namely, unfairness, real or alleged, in the incidence of the tribute; the absence of any peaceable means of settling disputes between the towns, except by the obviously unpopular method of appeal to the satrap; and, above all, the hated system of ruling them by means of tyrants who acted as political agents for the Persians.