For this purpose he might, at least with more prospect of success, reckon on the leaders of the Spanish patriot army, on the connections which he had formed in Syracuse, and on the intervention of Philip. Everything depended on bringing new forces into the Italian field of war against Rome from Spain, Syracuse, or Macedonia; and for the attainment or for the prevention of this object wars were carried on in Spain, Sicily, and Greece. All of these were but means to an end, and historians have often erred in accounting them of greater importance. So far as the Romans were concerned, they were essentially defensive wars, the proper objects of which were to hold the passes of the Pyrenees, to detain the Macedonian army in Greece, to defend Messana and to bar the communication between Italy and Sicily. Of course this defensive warfare was, wherever it was possible, waged by offensive methods; and, should circumstances be favourable, it might develop into the dislodging of the Phoenicians from Spain and Sicily, and into the dissolution of Hannibal's alliances with Syracuse and with Philip. The Italian war in itself fell for the time being into the shade, and resolved itself into conflicts about fortresses and razzias, which had no decisive effect on the main issue. Nevertheless, so long as the Phoenicians retained the offensive at all, Italy always remained the central aim of operations; and all efforts were directed towards, as all interest centred in, the doing away, or perpetuating, of Hannibal's isolation in southern Italy.
Had it been possible, immediately after the battle of Cannae, to bring into play all the resources on which Hannibal thought that he might reckon, he might have been tolerably certain of success. But the position of Hasdrubal at that time in Spain after the battle on the Ebro was so critical, that the supplies of money and men, which the victory of Cannae had roused the Carthaginian citizens to furnish, were for the most part expended on Spain, without producing much improvement in the position of affairs there. The Scipios transferred the theatre of war in the following campaign (539) from the Ebro to the Guadalquivir; and in Andalusia, in the very centre of the proper Carthaginian territory, they achieved at Illiturgi and Intibili two brilliant victories. In Sardinia communications entered into with the natives led the Carthaginians to hope that they should be able to master the island, which would have been of importance as an intermediate station between Spain and Italy. But Titus Manlius Torquatus, who was sent with a Roman army to Sardinia, completely destroyed the Carthaginian landing force, and reassured to the Romans the undisputed possession of the island (539). The legions from Cannae sent to Sicily held their ground in the north and east of the island with courage and success against the Carthaginians and Hieronymus; the latter met his death towards the end of 539 by the hand of an assassin. Even in the case of Macedonia the ratification of the alliance was delayed, principally because the Macedonian envoys sent to Hannibal were captured on their homeward journey by the Roman vessels of war. Thus the dreaded invasion of the east coast was temporarily suspended; and the Romans gained time to secure the very important station of Brundisium first by their fleet and then by the land army which before the arrival of Gracchus was employed for the protection of Apulia, and even to make preparations for an invasion of Macedonia in the event of war being declared. While in Italy the war thus came to a stand, out of Italy nothing was done on the part of Carthage to accelerate the movement of new armies or fleets towards the seat of war. The Romans, again, had everywhere with the greatest energy put themselves in a state of defence, and in that defensive attitude had fought for the most part with good results wherever the genius of Hannibal was absent. Thereupon the short-lived patriotism, which the victory of Cannae had awakened in Carthage, evaporated; the not inconsiderable forces which had been organized there were, either through factious opposition or merely through unskilful attempts to conciliate the different opinions expressed in the council, so frittered away that they were nowhere of any real service, and but a very small portion arrived at the spot where they would have been most useful. At the close of 539 the reflecting Roman statesman might assure himself that the urgency of the danger was past, and that the resistance so heroically begun had but to persevere in its exertions at all points in order to achieve its object.
First of all the war in Sicily came to an end. It had formed no part of Hannibal's original plan to excite a war on the island; but partly through accident, chiefly through the boyish vanity of the imprudent Hieronymus, a land war had broken out there, which - doubtless because Hannibal had not planned it - the Carthaginian council look up with especial zeal. After Hieronymus was killed at the close of 539, it seemed more than doubtful whether the citizens would persevere in the policy which he had pursued. If any city had reason to adhere to Rome, that city was Syracuse; for the victory of the Carthaginians over the Romans could not but give to the former, at any rate, the sovereignty of all Sicily, and no one could seriously believe that the promises made by Carthage to the Syracusans would be really kept. Partly induced by this consideration, partly terrified by the threatening preparations of the Romans - who made every effort to bring once more under their complete control that important island, the bridge between Italy and Africa, and now for the campaign of 540 sent their best general, Marcus Marcellus, to Sicily - the Syracusan citizens showed a disposition to obtain oblivion of the past by a timely return to the Roman alliance. But, amidst the dreadful confusion in the city - which after the death of Hieronymus was agitated alternately by endeavours to re-establish the ancient freedom of the people and by the coups de main of the numerous pretenders to the vacant throne, while the captains of the foreign mercenary troops were the real masters of the place - Hannibal's dexterous emissaries, Hippocrates and Epicydes, found opportunity to frustrate the projects of peace. They stirred up the multitude in the name of liberty; descriptions, exaggerated beyond measure, of the fearful punishment that the Romans were said to have inflicted on the Leontines, who had just been re-conquered, awakened doubts even among the better portion of the citizens whether it was not too late to restore their old relations with Rome; while the numerous Roman deserters among the mercenaries, mostly runaway rowers from the fleet, were easily persuaded that a peace on the part of the citizens with Rome would be their death-warrant. So the chief magistrates were put to death, the armistice was broken, and Hippocrates and Epicydes undertook the government of the city. No course was left to the consul except to undertake a siege; but the skilful conduct of the defence, in which the Syracusan engineer Archimedes, celebrated as a learned mathematician, especially distinguished himself, compelled the Romans after besieging the city for eight months to convert the siege into a blockade by sea and land.