On more than one occasion the Athenians derived, or at least believed themselves to have derived, important benefits from this marriage of Boreas with the daughter of their primæval hero: one inestimable service, rendered at a juncture highly critical for Grecian independence, deserves to be specified.[474] At the time of the invasion of Greece by Xerxês, the Grecian fleet was assembled at Chalcis and Artemision in Eubœa, awaiting the approach of the Persian force, so overwhelming in its numbers as well by sea as on land. The Persian fleet had reached the coast of Magnêsia and the south-eastern corner of Thessaly without any material damage, when the Athenians were instructed by an oracle “to invoke the aid of their son-in-law.” Understanding the advice to point to Boreas, they supplicated his aid and that of Oreithyia, most earnestly, as well by prayer as by sacrifice,[475] and the event corresponded to their wishes. A furious north-easterly wind immediately arose, and continued for three days to afflict the Persian fleet as it lay on an unprotected coast: the number of ships driven ashore, both vessels of war and of provision, was immense, and the injury done to the armament was never thoroughly repaired. Such was the powerful succor which the Athenians derived, at a time of their utmost need, from their son-in-law Boreas; and their gratitude was shown by consecrating to him a new temple on the banks of the Ilissus. [474] Herodot. vii. 189. Οἱ δ᾽ ὦν Ἀθηναῖοί σφι λέγουσι βοηθήσαντα τὸν Βορῆν πρότερον, καὶ τότε ἐκεῖνα κατεργάσασθαι· καὶ ἱρὸν ἀπελθόντες Βορέω ἱδρύσαντο παρὰ ποταμὸν Ἴλισσον. [475] Herodot. _l. c._ Ἀθηναῖοι τὸν Βορῆν ἐκ θεοπροπίου ἐπεκαλέσαντο, ἐλθόντος σφι ἄλλου χρηστηρίου, τὸν γαμβρὸν ἐπίκουρον καλέσασθαι. Βορῆς δὲ, κατὰ τὸν Ἑλλήνων λόγον ἔχει γυναῖκα Ἀττικὴν, Ὠρειθυίην τὴν Ἐρεχθῆος. Κατὰ δὴ τὸ κῆδος τοῦτο, οἱ Ἀθηναῖοι, συμβαλλεόμενοί σφι τὸν Βορῆν γαμβρὸν εἶναι, etc.