Slowly the Persian army moved southward through Thessaly. A handful of Spartans, under Leonidas, had been sent forward to delay the Persian advance. They held the Pass of Thermopylæ, between the eastern shoulder of Mount Æta and the sea. It was a hopeless position. To fight there at all with such an insignificant force was a mistake. But the Government of Sparta, slaves to tradition, could not grasp the idea of the plans proposed by the great Athenian. They were half persuaded to recall Leonidas, but hesitated to act until it was too late. The Spartan chief and his few hundred warriors died at their post in self-sacrificing obedience to the letter of their orders. The Persians poured over the Pass and inundated the plains of Attica. The few Athenians who had persisted in defending the Acropolis of Athens made only a brief resistance against overwhelming numbers. They were all put to the sword and their fellow-countrymen in the island of Salamis saw far off the pall of smoke that hung over their city, where temples and houses alike were sacked and set on fire by the victors. The winds and waves had already been fighting for the Greeks. The Persian war fleet of 1200 great ships had coasted southwards by the shores of Thessaly till they neared the group of islands off the northern point of Euboea. Their scouts reported a Greek fleet to be lying in the channel between the large island and the mainland. Night was coming on, and the Persians anchored in eight long lines off Cape Sepias. As the sun rose there came one of those sudden gales from the eastward that are still the terror of small craft in the Archipelago. A modern sailor would try to beat out to seaward and get as far as possible from the dangerous shore, but these old-world seamen dreaded the open sea. They tried to ride out the gale, but anchors dragged and hundreds of ships were piled in shattered masses on the shore. Some were stranded in positions where they could be repaired and refloated as the weather cleared up; but by the evening of the third day, when at last the wind fell, only eight hundred galleys of the Persian armada were still in seaworthy fighting condition. Here, as on other occasions, the very numbers of the Persian fleet proved a source of danger to it. The harbours that could give shelter to this multitude of ships were very few and far between, nor was it an easy matter to find that other refuge of the ancient navigator--a beach of easy slope and sufficiently wide extent to enable the ships to be dragged out of the water and placed high and dry beyond the reach of the angriest waves. The fact that ships were beached and hauled up the shore during bad weather, and in winter, limited their size, and in both the Persian and the Greek fleets there probably was not a ship much bigger than the barges we see on our canals, or as big as some of the largest sea-going barges.