I think we may be safe in saying that no forces as large as these, in the number of men enrolled in them, had ever before been collected for a military purpose, and also that no former expedition had ever been planned with so much care and forethought. Xerxes made two bridges for the passing of his army across the Hellespont; he cut a canal through the Isthmus at Mount Athos for the passage of his fleet. The fleet, you see, if you will look at the map, would coast round along the south of Thrace, accompanying the army, till it came to the Peninsula at the end of which is Mount Athos. Xerxes had established stations in Thrace for the supply of his army with food and all needful things as it went along. It was just off Mount Athos that the storm had scattered the fleet of the former expedition that he had sent against Greece. By making this canal, and so letting the ships go through the Isthmus, he avoided the danger of another storm off the end of the Peninsula. But there were other dangers besides those from {134} the wind and waves, for a fleet in any part of the Mediterranean. Although the Persian monarch might style himself King of Kings, there was another power that ruled the sea at this time, the power of Carthage, that colony of the Phœnicians of which I asked you to take note the first time that it found a place in this story. The Phœnicians, as we have seen, had planted colonies of their own at all convenient places along the Mediterranean shore, and of all these Carthage had grown to be by far the strongest in its numbers. It was regarded as the capital city, the headquarters, of all that half-merchant and half-pirate host which we have seen always going to and fro on the waters of the great inland sea. For fifty years and more before the battle of Marathon was fought it had become a great power, the chief naval power of the world, and it had already come into collision with the Greeks.