of Miltiades, when defending himself on the charge of "tyranny" after his retirement to Athens. We cannot be sure of these things, and it is not necessary here to discuss how much he knew of the geography of the lands beyond the Danube. It is what happened on the left bank of that river that affected the Greeks. Darius crossed the Thracian Bosporus and marched north to the Danube, on which a bridge of ships had been prepared. In his army were contingents from many Greek states under their respective tyrants. He seems to have been fully aware of the difficulties in the way of his design, which, according to Herodotus, was to march round the head of the Euxine and re-enter Asia through Colchis along its eastern shore. In the absence of all certain knowledge of the country, the rivers, the wild tribes to be encountered, he wisely resolved to keep a retreat open by maintaining the bridge of ships across the Danube. It shows some confidence in the Greek character, or in the hold he had upon the men themselves, that he entrusted the maintenance and defence of this bridge to the tyrants of the Greek towns with some of their own troops. Herodotus says that this was suggested by Goes, the commander of the contingent from Mitylene, in Lesbos. It is such an obvious precaution that he must be held likely to have thought of it himself. The selection of the Greek tyrants for the service may have been due to Coes. His direction to them was to wait sixty days, to be reckoned by the daily untying of a knot in a leathern thong, and if he had not returned by that time, to break up the bridge and sail home. The sixty days passed, and,
