The expedition to Thasos was attended with a circumstance which first gives token of the coming hostilities between Sparta and Athens. At an early period of the blockade the Thasians secretly applied to the Lacedaemonians to make a diversion in their favour by invading Attica: and though the Lacedaemonians were still ostensibly allied with Athens, they were base enough to comply with this request. Their treachery, however, was prevented by a terrible calamity which befel themselves. In the year B.C. 461 their capital was visited by an earthquake which laid it in ruins and killed 20,000 of the citizens. But this was only part of the calamity. The earthquake was immediately followed by a revolt of the Helots, who were always ready to avail themselves of the weakness of their tyrants. Being joined by the Messenians, they fortified themselves in Mount Ithome in Messenia. Hence this revolt is sometimes called the Third Messenian War (B.C. 464). after two or three years spent in a vain attempt to dislodge them from this position, the Lacedaemonians found themselves obliged to call in the assistance of their allies, and, among the rest, of the Athenians. It was with great difficulty that Cimon persuaded the Athenians to comply with this request; but he was at length despatched to Laconia with a force of 4000 hoplites. The aid of the Athenians had been requested by the Lacedaemonians on account of their acknowledged superiority in the art of attacking fortified places. As, however, Cimon did not succeed in dislodging the Helots from Ithome the Lacedaemonians, probably from a consciousness of their own treachery in the affair of Thasos, suspected that the Athenians were playing them false, and abruptly dismissed them, saying that they had no longer any occasion for their services. This rude dismissal gave great offence at Athens, and annihilated for a time the political influence of Cimon. The democratical party had from the first opposed the expedition; and it afforded them a great triumph to be able to point to Cimon returning not only unsuccessful but insulted. That party was now led by Pericles. A sort of hereditary feud existed between Pericles and Cimon; for it was Xanthippus, the father of Pericles, who had impeached Miltiades, the father of Cimon. The character of Pericles was almost the reverse of Cimon's. Although the leader of the popular party, his manners were reserved. He appeared but little in society, and only in public upon great occasions. His mind had received the highest polish which that period was capable of giving. He constantly conversed with Anaxagoras, Protagoras, Zeno, and other eminent philosophers. To oratory in particular he had devoted much attention, as an indispensable instrument for swaying the public assemblies of Athens.