At the chief seat of war, in Campania, the struggle went on with very varying success. The legions posted in the neighbourhood of Capua had not yet strictly invested the city, but had so greatly hindered the cultivation of the soil and the ingathering of the harvest, that the populous city was in urgent need of supplies from without. Hannibal accordingly collected a considerable supply of grain, and directed the Campanians to receive it at Beneventum; but their tardiness gave the consuls Quintus Flaccus and Appius Claudius time to come up, to inflict a severe defeat on Hanno who protected the grain, and to seize his camp and all his stores. The two consuls then invested the town, while Tiberius Gracchus stationed himself on the Appian Way to prevent Hannibal from approaching to relieve it But that brave officer fell in consequence of the shameful stratagem of a perfidious Lucanian; and his death was equivalent to a complete defeat, for his army, consisting mostly of those slaves whom he had manumitted, dispersed after the fall of their beloved leader. So Hannibal found the road to Capua open, and by his unexpected appearance compelled the two consuls to raise the blockade which they had barely begun. Their cavalry had already, before Hannibal's arrival, been thoroughly defeated by the Phoenician cavalry, which lay as a garrison in Capua under Hanno and Bostar, and by the equally excellent Campanian horse. The total destruction of the regular troops and free bands in Lucania led by Marcus Centenius, a man imprudently promoted from a subaltern to be a general, and the not much less complete defeat of the negligent and arrogant praetor Gnaeus Fulvius Flaccus in Apulia, closed the long series of the misfortunes of this year. But the stubborn perseverance of the Romans again neutralized the rapid success of Hannibal, at least at the most decisive point. As soon as Hannibal turned his back on Capua to proceed to Apulia, the Roman armies once more gathered around that city, one at Puteoli and Volturnum under Appius Claudius, another at Casilinum under Quintus Fulvius, and a third on the Nolan road under the praetor Gaius Claudius Nero. The three camps, well entrenched and connected with one another by fortified lines, precluded all access to the place, and the large, inadequately provisioned city could not but find itself compelled by the mere investment to surrender at no distant time, should no relief arrive. As the winter of 542-3 drew to an end, the provisions were almost exhausted, and urgent messengers, who were barely able to steal through the well-guarded Roman lines, requested speedy help from Hannibal, who was at Tarentum, occupied with the siege of the citadel. With 33 elephants and his best troops he departed by forced marches from Tarentum for Campania, captured the Roman post at Caiatia, and took up his camp on Mount Tifata close by Capua, in the confident expectation that the Roman generals would, now raise the siege as they had done the year before. But the Romans, who had had time to entrench their camps and their lines like a fortress, did not stir, and looked on unmoved from their ramparts, while on one side the Campanian horsemen, on the other the Numidian squadrons, dashed against their lines. A serious assault could not be thought of by Hannibal; he could foresee that his advance would soon draw the other Roman armies after him to Campania, if even before their arrival the scarcity of supplies in a region so systematically foraged did not drive him away. Nothing could be done in that quarter.

Hannibal tried a further expedient, the last which occurred to his inventive genius, to save the important city. After giving the Campanians information of his intention and exhorting them to hold out, he started with the relieving army from Capua and took the road for Rome. With the same dexterous boldness which he had shown in his first Italian campaigns, he threw himself with a weak army between the armies and fortresses of the enemy, and led his troops through Samnium and along the Valerian Way past Tibur to the bridge over the Anio, which he passed and encamped on the opposite bank, five miles from the city. The children's children of the Romans still shuddered, when they were told of "Hannibal at the gate"; real danger there was none. The country houses and fields in the neighbourhood of the city were laid waste by the enemy; the two legions in the city, who went forth against them, prevented the investment of the walls. Besides, Hannibal had never expected to surprise Rome by a coup de main, such as Scipio soon afterwards executed against New Carthage, and still less had he meditated a siege in earnest; his only hope was that in the first alarm part of the besieging army of Capua would march to Rome and thus give him an opportunity of breaking up the blockade. Accordingly after a brief stay he departed. The Romans saw in his withdrawal a miraculous intervention of the gods, who by portents and visions had compelled the wicked man to depart, when in truth the Roman legions were unable to compel him; at the spot where Hannibal had approached nearest to the city, at the second milestone on the Appian Way in front of the Capene gate, with grateful credulity the Romans erected an altar to the god "who turned back and protected" (Rediculus Tutanus), Hannibal in reality retreated, because this was part of his plan, and directed his march towards Capua. But the Roman generals had not committed the mistake on which their opponent had reckoned; the legions remained unmoved in the lines round Capua, and only a weak corps had been detached on the news of Hannibal's march towards Rome. When Hannibal learned this, he suddenly turned against the consul Publius Galba, who had imprudently followed him from Rome, and with whom he had hitherto avoided an engagement, vanquished him, and took his camp by storm.

But this was a poor compensation for the now inevitable fall of Capua. Long had its citizens, particularly the better passes, anticipated with sorrowful forebodings what was coming; the senate-house and the administration of the city were left almost exclusively to the leaders of the popular party hostile to Rome. Now despair seized high and low, Campanians and Phoenicians alike. Twenty-eight senators chose a voluntary death; the remainder gave over the city to the discretion of an implacably exasperated foe. Of course a bloody retribution had to follow; the only discussion was as to whether the process should be long or short: whether the wiser and more appropriate course was to probe to the bottom the further ramifications of the treason even beyond Capua, or to terminate the matter by rapid executions. Appius Claudius and the Roman senate wished to take the former course; the latter view, perhaps the less inhuman, prevailed. Fifty-three of the officers and magistrates of Capua were scourged and beheaded in the marketplaces of Cales and Teanum by the orders and before the eyes of the proconsul Quintus Flaccus, the rest of the senators were imprisoned, numbers of the citizens were sold into slavery, and the estates of the more wealthy were confiscated. Similar penalties were inflicted upon Atella and Caiatia. These punishments were severe; but, when regard is had to the importance of the revolt of Capua from Rome, and to what was the ordinary if not warrantable usage of war in those times, they were not unnatural. And had not the citizens themselves pronounced their own sentence, when immediately after their defection they put to death all the Roman citizens present in Capua at the time of the revolt? But it was unjustifiable in Rome to embrace this opportunity of gratifying the secret rivalry that had long subsisted between the two largest cities of Italy, and of wholly annihilating, in a political point of view, her hated and envied competitor by abolishing the constitution of the Campanian city.