while to save the fleet one great danger a canal was cut across the isthmus of Mount Athos. The march began early in B.C. 480; the Hellespont was safely crossed, and the advance through Macedonia went steadily on, while the fleet made its way to Therma (Thessalonica).
The preparation of such a vast armament could not, of course, be unknown in Greece. A congress of representatives from the southern states met at Corinth in the autumn of B.C. 481. Their first measure was to send spies to Sardis to see whether the report was true. They were captured, but allowed by the king to see everything and return safe, in hope that their report might terrify the Greeks and prevent resistance. The congress had, indeed, a formidable state of things to face. Greece was disunited, and there was a powerful party in nearly all the country north of Attica which was prepared from fear or disaffection to welcome the invaders. The seaboard of Thrace and Macedonia was already subject to the king; most of the islands of the Ægean had been compelled to submit and even to furnish him with ships. In Thessaly the powerful clan of the Aleuadae of Larisa had invited the invasion, and though there was a loyal party in Thessaly, it was too weak to resist. Only two states in Boeotia stood out—Plataea and Thespiae, while the Phocians were divided and useless. Nor did the congress succeed in getting support elsewhere. The Argives refused all help. The Cretans evaded a direct promise by a reference to Delphi. In the West, Gelo of Syracuse, the most powerful sovereign in Sicily, would only help on con-
