In like manner the Carthaginians already at the end of the second century of Rome established themselves in Sardinia, which was utilized by them precisely in the same way as Libya. While the natives withdrew into the mountainous interior of the island to escape from bondage as agricultural serfs, just as the Numidians in Africa withdrew to the borders of the desert, Phoenician colonies were conducted to Caralis (Cagliari) and other important points, and the fertile districts along the coast were turned to account by the introduction of Libyan cultivators.

Lastly in Sicily the straits of Messana and the larger eastern half of the island had fallen at an early period into the hands of the Greeks; but the Phoenicians, with the help of the Carthaginians, retained the smaller adjacent islands, the Aegates, Melita, Gaulos, Cossyra - the settlement in Malta especially was rich and flourishing - and they kept the west and north-west coast of Sicily, whence they maintained communication with Africa by means of Motya and afterwards of Lilybaeum and with Sardinia by means of Panormus and Soluntum. The interior of the island remained in the possession of the natives, the Elymi, Sicani, and Siceli. After the further advance of the Greeks was checked, a state of comparative peace had prevailed in the island, which even the campaign undertaken by the Carthaginians at the instigation of the Persians against their Greek neighbours on the island (274) did not permanently interrupt, and which continued on the whole to subsist till the Attic expedition to Sicily (339-341). The two competing nations made up their minds to tolerate each other, and confined themselves in the main each to its own field.

All these settlements and possessions were important enough in themselves; but they were of still greater moment, inasmuch as they became the pillars of the Carthaginian maritime supremacy. By their possession of the south of Spain, of the Baleares, of Sardinia, of western Sicily and Melita, and by their prevention of Hellenic colonies on the east coast of Spain, in Corsica, and in the region of the Syrtes, the masters of the north coast of Africa rendered their sea a closed one, and monopolized the western straits. In the Tyrrhene and Gallic seas alone the Phoenicians were obliged to admit the rivalry of other nations. This state of things might perhaps be endured, so long as the Etruscans and the Greeks served to counterbalance each other in these waters; with the former, as the less dangerous rivals, Carthage even entered into an alliance against the Greeks. But when, on the fall of the Etruscan power - a fall which, as is usually the case in such forced alliances, Carthage had hardly exerted all her power to avert - and after the miscarriage of the great projects of Alcibiades, Syracuse stood forth as indisputably the first Greek naval power, not only did the rulers of Syracuse naturally begin to aspire to dominion over Sicily and lower Italy and at the same time over the Tyrrhene and Adriatic seas, but the Carthaginians also were compelled to adopt a more energetic policy. The immediate result of the long and obstinate conflicts between them and their equally powerful and infamous antagonist, Dionysius of Syracuse (348-389), was the annihilation or weakening of the intervening Sicilian states - a result which both parties had an interest in accomplishing - and the division of the island between the Syracusans and Carthaginians. The most flourishing cities in the island - Selinus, Himera, Agrigentum, Gela, and Messana - were utterly destroyed by the Carthaginians in the course of these unhappy conflicts: and Dionysius was not displeased to see Hellenism destroyed or suppressed there, so that, leaning for support on foreign mercenaries enlisted from Italy, Gaul and Spain, he might rule in greater security over provinces which lay desolate or which were occupied by military colonies. The peace, which was concluded after the victory of the Carthaginian general Mago at Kronion (371), and which subjected to the Carthaginians the Greek cities of Thermae (the ancient Himera), Segesta, Heraclea Minoa, Selinus, and a part of the territory of Agrigentum as far as the Halycus, was regarded by the two powers contending for the possession of the island as only a temporary accommodation; on both sides the rivals were ever renewing their attempts to dispossess each other. Four several times - in 360 in the time of Dionysius the elder; in 410 in that of Timoleon; in 445 in that of Agathocles; in 476 in that of Pyrrhus - the Carthaginians were masters of all Sicily excepting Syracuse, and were baffled by its solid walls; almost as often the Syracusans, under able leaders, such as were the elder Dionysius, Agathocles, and Pyrrhus, seemed equally on the eve of dislodging the Africans from the island. But more and more the balance inclined to the side of the Carthaginians, who were, as a rule, the aggressors, and who, although they did not follow out their object with Roman steadfastness, yet conducted their attack with far greater method and energy than the Greek city, rent and worn out by factions, conducted its defence. The Phoenicians might with reason expect that a pestilence or a foreign condottiere would not always snatch the prey from their hands; and for the time being, at least at sea, the struggle was already decided[5]: the attempt of Pyrrhus to re-establish the Syracusan fleet was the last. After the failure of that attempt, the Carthaginian fleet commanded without a rival the whole western Mediterranean; and their endeavours to occupy Syracuse, Rhegium, and Tarentum, showed the extent of their power and the objects at which they aimed. Hand in hand with these attempts went the endeavour to monopolize more and more the maritime commerce of this region, at the expense alike of foreigners and of their own subjects; and it was not the wont of the Carthaginians to recoil from any violence that might help forward their purpose. A contemporary of the Punic wars, Eratosthenes, the father of geography (479-560), affirms that every foreign mariner sailing towards Sardinia or towards the Straits of Gades, who fell into the hands of the Carthaginians, was thrown by them into the sea; and with this statement the fact completely accords, that Carthage by the treaty of 406[6] declared the Spanish, Sardinian, and Libyan ports open to Roman trading vessels, whereas by that of 448[7], it totally closed them, with the exception of the port of Carthage itself, against the same.

Aristotle, who died about fifty years before the commencement of the first Punic war, describes the constitution of Carthage as having changed from a monarchy to an aristocracy, or to a democracy inclining towards oligarchy, for he designates it by both names. The conduct of affairs was immediately vested in the hands of the Council of Ancients, which, like the Spartan gerusia, consisted of the two kings nominated annually by the citizens, and of twenty-eight gerusiasts, who were also, as it appears, chosen annually by the citizens. It was this council which mainly transacted the business of the state-making, for instance, the preliminary arrangements for war, appointing levies and enlistments, nominating the general, and associating with him a number of gerusiasts from whom the sub-commanders were regularly taken; and to it despatches were addressed. It is doubtful whether by the side of this small council there existed a larger one; at any rate it was not of much importance. As little does any special influence seem to have belonged to the kings; they acted chiefly as supreme judges, and they were frequently so named (shofetes, praetores). The power of the general was greater. Isocrates, the senior contemporary of Aristotle, says that the Carthaginians had an oligarchical government at home, but a monarchical government in the field; and thus the office of the Carthaginian general may be correctly described by Roman writers as a dictatorship, although the gerusiasts attached to him must have practically at least restricted his power and, after he had laid down his office, a regular official reckoning - unknown among the Romans - awaited him. There existed no fixed term of office for the general, and for this very reason he was doubtless different from the annual king, from whom Aristotle also expressly distinguishes him. The combination however of several offices in one person was not unusual among the Carthaginians, and it is not therefore surprising that often the same person appears as at once general and shofete.