In its wars with Sparta Argos sought more than once to take advantage of the religious scruples of the enemy. This happened especially in connection with the festival of Carnean Apollo (a deity worshipped by them both), the date of which the Argives varied to suit their own convenience, alleging the celebration of it as a reason why military operations should be suspended. To guard against such strategy, Agesipolis, the Spartan king, on one occasion obtained authority from the oracles of Delphi and Olympia to disregard such a fictitious claim. Having crossed the border he was challenged by two heralds wearing the insignia of their office, on the ground that it was a time of holy truce; to which Agesipolis replied that he had the warrant of the gods to disobey their commands. The same evening there was a shock of earthquake, whereupon the Spartans sang the pæan to Apollo and expected an order to retreat; but the king declared that as the earthquake had not happened till after he had crossed the frontier he regarded it as a favourable omen. He proceeded to ravage the country, and had reached the gates of Argos when a flash of lightning killed several of his men, whereupon he at once beat a retreat. In the previous century a great outrage upon religion had been committed by a Spartan king, Cleomenes, who afterwards went mad and committed suicide. Having driven 6000 Argive troops into the sacred grove of Apollo, close to the city, he set fire to the grove and put the 6000 men to death, inducing many of them to quit their place of refuge on the understanding that their lives would be spared. He then went with a thousand men to the temple of Hera, a few miles distant, and insisted on sacrificing to the goddess in spite of the rule of the sanctuary, by which it was forbidden to strangers; and when admission was refused he caused the priest to be dragged from the altar and scourged. To the great displeasure of his countrymen, however, he carried the war against Argos no farther, alleging as his reason that the light on the altar had flashed upon him from the bosom of the statue of the goddess, not from her head. Although the chief Dorian temple in the district was that on the summit of Larissa in honour of Apollo, the Heræum, just referred to, was a much more ancient sanctuary, and was probably the original seat of the worship of Hera in Greece. Of this we have a token in the discovery among its ruins of an Egyptian scarab with cartouche, supposed to be of Thothmes III. (fifteenth century B.C.). Thucydides reckoned the date of the Peloponnesian war by the priestly registers in this temple, which seem to have been even older than the Olympian lists. The earliest priestess is said to have been Io, identified with the moon, whom Zeus transformed into a cow, and whose wanderings, imposed upon her by the jealous goddess, extended to the crossing of the Thracian straits, thence called Bosporus (Ox-ford or Cow-ford).