Lastly, the changes which the altered position and increased responsibilities of Rome had effected in her military system tended to weaken the intimate connection between the Roman army in the field and the Roman people at home, and thus pre pared the way for that complete breach between the two which in the end proved fatal to the republic. It is true that service in the legion was still the first duty and the highest privilege of the fully qualified citizen. But this service was gradually altering in char acter. Though new legions were still raised each year for the summer campaigns, this was by no means always accompanied, as formerly, by the disbandment of those already on foot, and this increase in the length of time during which the citizen was kept with the standards had, as early as the siege of Veii, necessitated a further deviation from the old theory of military service—the introduction of pay. Moreover, while in the early days of the republic the same divisions served for the soldier in the legion and the citizen in the assembly, in the new manipular system, with its three lines, no regard was paid to civic distinctions, but only to length of service and military efficiency, while at the same time the more open order of fighting which it involved demanded of each soldier greater skill, and therefore a more thorough train ing in arms than the old phalanx. One other change resulted from the new military necessities of the time, which was as fruitful of results as the incipient separation between the citizen and the soldier. Under the early republic, the chief command of the legions rested with the consuls of the year. But, as Rome's military operations increased in area and in distance from Rome, a larger staff became necessary, and the inconvenience of summon ing home a consul in the field from an unfinished campaign became intolerable. The remedy found, that of prolonging for a further period the imperium of the consul, was first applied in 327 B.C. in the case of Q. Publilius Philo, and between 327 and 264 instances of this prorogatio imperii became increasingly common. This proconsular authority, originally an occasional and subordinate one, was destined to become first of all the strongest force in the Republic, and ultimately the chief prop of the power of the Caesars.
Period B: Rome and the Mediterranean States, 265-146 B.C.—(a) Conquest of the West.—Though marked out by her geographical position as the natural centre of the Mediterranean, Italy had hitherto played no active part in the Mediterranean politics, but, now that she was for the first time united, it was felt throughout the Mediterranean world that a new Power had arisen, and Rome, as the head and representative of Italy, found herself irresistibly drawn into the vortex of Mediterranean affairs. Egypt sought her alliance, and Greek scholars began to interest themselves keenly in the history, constitution and character of the Latin republic which had so suddenly become famous. But Rome looked naturally westwards rather than eastwards. The western coasts of the peninsula were the most fertile and popu lous and wealthy ; and it was in this direction that the natural openings for Italian commerce were to be found. It was, however, precisely on this side that Rome had serious ground for anxiety. Carthage was now at the height of her power. Her outposts were threateningly near to Italy in Sardinia and in Sicily, while her fleets swept the seas and jealously guarded for the benefit of Carthage alone the hidden treasures of the West. In the east of Sicily, Syracuse still upheld the cause of Greek independence against the hereditary foe of the Greek race; but Syracuse stood alone, and her resources were comparatively small. What Rome had to fear was the establishment, and that at no distant date, of an absolute Carthaginian domination over the western seas—a dom ination which would not only be fatal to Italian commerce, but would be a standing menace to the safety of the Italian coasts.
First Punic War, 265-241.—It was above all things essential for Rome that the Carthaginians should advance no farther east wards. But in 265 Rome was threatened with the establishment of Carthaginian rule at Messana, within sight of the Italian coast.
The intervention of both powers in a quarrel between the Mamer tines, a body of Campanian mercenaries who had occupied Messana, and Hieron II. of Syracuse, led to the outbreak of war between Rome and Carthage in 264 B.C. The military history of the struggle which followed is treated in the article PUNIC WARS; it will suffice to note here that the war lasted until 241 B.C., when the Carthaginians were compelled to cede Sicily and the Lipari islands to Rome, and to pay an indemnity of 3,20o talents (about £800,000).
The struggle was one in which both Rome and Carthage were serving an apprenticeship in a warfare the conditions of which were unfamiliar to both. The Roman legions were foes very un like any against which the Carthaginian leaders had ever led their motley array of mercenaries, while Rome was called upon for the first time to fight a war across the sea, and to fight with ships against the greatest naval power of the age. The chief dangers for Carthage lay obviously in the jealousy exhibited at home of her officers abroad, in the difficulty of controlling her mercenary troops, and in the ever-present possibility of dis affection among her subjects in Libya—dangers which even the genius of Hannibal failed finally to surmount. Rome, on the other hand, was strong in the public spirit of her citizens, the fidelity of her allies, the valour and discipline of her legions. What she needed was a system which would make a better use of her splendid materials than one under which her plans were shaped from day to day by a divided senate, and executed by officers who were changed every year, and by soldiers most of whom returned home at the close of each summer's campaign.
The interval between the first and second Punic Wars was employed by both Rome and Carthage in strengthening their respective positions. The eastern end of Sicily was still left under the rule of Hieron as the ally of Rome, but the larger western portion of the island became directly subject to Rome, and a temporary arrangement seems to have been made for its govern ment, either by one of the two praetors, or possibly by a quaestor. Sardinia and Corsica had not been surrendered to Rome by the treaty of 241, but three years later (239), on the invitation of the Carthaginian mercenaries stationed in the islands, a Roman force occupied them ; Carthage protested, but, on the Romans threat ening war, she gave way, and Sardinia and Corsica were formally ceded to Rome, though it was some seven or eight years before all resistance on the part of the natives themselves was crushed. In 227, however, the senate considered matters ripe for the es tablishment of a separate administration in her oversea posses sions. In that year two additional praetors were elected; to one was assigned the charge of western Sicily, to the other that of Sardinia and Corsica, and thus the first stones of the Roman pro vincial system were laid. Of at least equal importance for the security of the peninsula was the subjugation of the Celtic tribes in the valley of the Po. These, headed by the Boii and Insubres and assisted by levies from the Celts to the westward, had in 225 alarmed the whole of Italy by invading Etruria and penetrating to Clusium, only three days' journey from Rome. Here, how ever, their courage seems to have failed them. They retreated northwards along the Etruscan coast, until at Telamon their way was barred by the Roman legions returning from Sardinia to the defence of Rome, while a second consular army hung upon their rear. Thus hemmed in, the Celts fought desperately, but were completely defeated and the flower of their tribesmen slain. The Romans followed up their success by invading the Celtic territory. The Boii were easily reduced to submission. The Insubres, north of the Po, resisted more obstinately, but by 222 the war was over, and all the tribes in the rich Po valley acknowledged the suprem acy of Rome. The conquered Celts were not enrolled among the Italian allies of Rome, but were treated as subjects beyond the frontier. Two colonies were founded to hold them in check— Placentia (218) and Cremona in the territory of the Insubres and the great northern road (Via Flaminia) was completed as far as the Celtic border at Ariminum.