Athens and Sparta were now quite the greatest powers in Greece.  No other state had dared to make head against the Persians, and all the lesser cities, and the isles and colonies, were anxious to obtain the help and friendship of one or other as their allies.  The two states were always rivals, and never made common cause, except when the Persian enemy was before them.  In the year 464 there was a terrible earthquake in Laconia, which left only five houses standing in Sparta, and buried great numbers in the ruins.  The youths, who were all together in one building exercising themselves, were almost all killed by its fall; and the disaster would have been worse if the king, Archidamas, had not caused the trumpet to be blown, as if to call the people to arms, just outside the city.  This brought all the men in order together just in time, for the Helots were rising against them, and, if they had found them groping each in the ruins of his house, might have killed them one by one; whereas, finding them up and armed, the slaves saw it was in vain, and dispersed.