The Romans achieved the sovereignty of Italy, because they strove for it; the hegemony--and the sovereignty which grew out of it--over the territories of the Mediterranean was to a certain extent thrown into the hands of the Romans by the force of circumstances without intention on their part to acquire it.
Out Of Italy
The immediate results of the war out of Italy were, the conversion of Spain into two Roman provinces--which, however, were in perpetual insurrection; the union of the hitherto dependent kingdom of Syracuse with the Roman province of Sicily; the establishment of a Roman instead of a Carthaginian protectorate over the most important Numidian chiefs; and lastly the conversion of Carthage from a powerful commercial state into a defenceless mercantile town. In other words, it established the uncontested hegemony of Rome over the western region of the Mediterranean. Moreover, in its further development, it led to that necessary contact and interaction between the state systems of the east and the west, which the first Punic war had only foreshadowed; and thereby gave rise to the proximate decisive interference of Rome in the conflicts of the Alexandrine monarchies.
In Italy
As to its results in Italy, first of all the Celts were now certainly, if they had not been already beforehand, destined to destruction; and the execution of the doom was only a question of time. Within the Roman confederacy the effect of the war was to bring into more distinct prominence the ruling Latin nation, whose internal union had been tried and attested by the peril which, notwithstanding isolated instances of wavering, it had surmounted on the whole in faithful fellowship; and to depress still further the non-Latin or non-Latinized Italians, particularly the Etruscans and the Sabellians of Lower Italy. The heaviest punishment or rather vengeance was inflicted partly on the most powerful, partly on those who were at once the earliest and latest, allies of Hannibal--the community of Capua, and the land of the Bruttians. The Capuan constitution was abolished, and Capua was reduced from the second city into the first village of Italy; it was even proposed to raze the city and level it with the ground. The whole soil, with the exception of a few possessions of foreigners or of Campanians well disposed towards Rome, was declared by the senate to be public domain, and was thereafter parcelled out to small occupiers on temporary lease. The Picentes on the Silarus were similarly treated; their capital was razed, and the inhabitants were dispersed among the surrounding villages. The doom of the Bruttians was still more severe; they were converted en masse into a sort of bondsmen to the Romans, and were for ever excluded from the right of bearing arms. The other allies of Hannibal also dearly expiated their offence. The Greek cities suffered severely, with the exception of the few which had steadfastly adhered to Rome, such as the Campanian Greeks and the Rhegines. Punishment not much lighter awaited the Arpanians and a number of other Apulian, Lucanian, and Samnite communities, most of which lost portions of their territory. On a part of the lands thus acquired new colonies were settled. Thus in the year 560 a succession of burgess-colonies was sent to the best ports of Lower Italy, among which Sipontum (near Manfredonia) and Croton may be named, as also Salernum placed in the former territory of the southern Picentes and destined to hold them in check, and above all Puteoli, which soon became the seat of the genteel -villeggiatura- and of the traffic in Asiatic and Egyptian luxuries. Thurii became a Latin fortress under the new name of Copia (560), and the rich Bruttian town of Vibo under the name of Valentia (562). The veterans of the victorious army of Africa were settled singly on various patches of land in Samnium and Apulia; the remainder was retained as public land, and the pasture stations of the grandees of Rome replaced the gardens and arable fields of the farmers. As a matter of course, moreover, in all the communities of the peninsula the persons of note who were not well affected to Rome were got rid of, so far as this could be accomplished by political processes and confiscations of property. Everywhere in Italy the non-Latin allies felt that their name was meaningless, and that they were thenceforth subjects of Rome; the vanquishing of Hannibal was felt as a second subjugation of Italy, and all the exasperation and all the arrogance of the victor vented themselves especially on the Italian allies who were not Latin. Even the colourless Roman comedy of this period, well subjected as it was to police control, bears traces of this. When the subjugated towns of Capua and Atella were abandoned without restraint to the unbridled wit of the Roman farce, so that the latter town became its very stronghold, and when other writers of comedy jested over the fact that the Campanian serfs had already learned to survive amidst the deadly atmosphere in which even the hardiest race of slaves, the Syrians, pined away; such unfeeling mockeries re-echoed the scorn of the victors, but not less the cry of distress from the down-trodden nations. The position in which matters stood is shown by the anxious carefulness, which during the ensuing Macedonian war the senate evinced in the watching of Italy, and by the reinforcements which were despatched from Rome to the most important colonies, to Venusia in 554, Narnia in 555, Cosa in 557, and Cales shortly before 570.
What blanks were produced by war and famine in the ranks of the Italian population, is shown by the example of the burgesses of Rome, whose numbers during the war had fallen almost a fourth. The statement, accordingly, which puts the whole number of Italians who fell in the war under Hannibal at 300,000, seems not at all exaggerated. Of course this loss fell chiefly on the flower of the burgesses, who in fact furnished the -elite- as well as the mass of the combatants. How fearfully the senate in particular was thinned, is shown by the filling up of its complement after the battle of Cannae, when it had been reduced to 123 persons, and was with difficulty restored to its normal state by an extraordinary nomination of 177 senators.