(M656) The Syracusans then prosecuted war with vigor against Naxos, which sided with Athens, until it was brought to a sudden close by an invasion of the Carthaginians, the ancient foes of Greece. As far back as the year 480 B.C.—that year which witnessed the invasion of Greece by Xerxes—the Carthaginians had invaded Sicily, with a mercenary army under Hamilcar, for the purpose of reinstating the tyrant of Himera, expelled by Theron of Agrigentum. The Carthaginian army was routed, and Hamilcar was slain by Gelon, the tyrant of Syracuse. This defeat was so signal, that it was seventy years before the Carthaginians again invaded Sicily, shortly after the destruction of Athenian power at Syracuse. No sooner was the protecting naval power of Athens withdrawn from Greece, than the Persians and the Carthaginians pressed upon the Hellenic world. (M657) It is singular that so little is known of the early history of Carthage, which became the great rival of Rome. It was founded by the Phœnicians, and became a considerable commercial city before Athens had reached the naval supremacy of Greece. Her possessions were extensive on the coast of Africa, both east and west, comprehending Sardinia and the Balearic isles. At the maximum of her power, before the first Punic war, the population was nearly a million of people. It was built on a fortified peninsula of about twenty miles in circumference, with the isthmus. Upon this isthmus was the citadel Byrsa, surrounded with a triple wall, and crowned at its summit by a magnificent temple of Æsculapius. It possessed three hundred tributary cities in Libya, which was but a small part of the great empire which belonged to it in the fourth century before Christ. All the towns on the coast, even those founded by the Phœnicians, like Hippo and Utica, were tributary, with the exception of Utica. Although the Carthaginians were averse to land service, yet no less than forty thousand hoplites, with one thousand cavalry and two thousand war chariots, marched out from the gates to resist an enemy. But the Carthaginian armies were mostly composed of mercenaries—Gauls, Iberians, and Libyans, and forming a discordant host in language and custom. (M658) The political constitution of Carthage was oligarchal. Two kings were elected annually, and presided over the Senate, of three hundred persons, made up from the principal families. The great families divided between them, as in Rome, the offices and influence of the State, and maintained an insolent distinction from the people. It was an aristocracy, based on wealth, and created by commerce, as in Venice, in the Middle Ages. There was a demos, or people, at Carthage, who were consulted on particular occasions; but, whether numerous or not, they were kept in dependence to the rich families by banquets and lucrative employments. The government was stable and well conducted, both for internal tranquillity and commercial aggrandizement.