Rome to the brink of collapse. Within a few weeks of Cannae a Roman army of 25,000 was ambushed by Boii Gauls at the battle of Silva Litana and annihilated. Fabius was elected consul in 215 BC and was re-elected in 214 BC. Roman allies defect, 216–207 BC Little survives of Polybius's account of Hannibal's army in Italy after Cannae and Livy is the best surviving source for this part of the war. Several of the city states in southern Italy allied with Hannibal or were captured when pro-Carthaginian factions betrayed their defences. These included the large city of Capua and the major port city of Tarentum (modern Taranto). Two of the major Samnite tribes also joined the Carthaginian cause. By 214 BC the bulk of southern Italy had turned against Rome, although there were many exceptions. The majority of Rome's allies in central Italy remained loyal. All except the smallest towns were too well fortified for Hannibal to take by assault and blockade could be a long-drawn-out affair, or, if the target was a port, impossible. Carthage's new allies felt little sense of community with Carthage, or even with each other. The new allies increased the number of places that Hannibal's army was expected to defend from Roman retribution, but provided relatively few fresh troops to assist him in doing so. Such Italian forces as were raised resisted operating away from their home cities and performed poorly when they did. When the port city of Locri defected to Carthage in the summer of 215BC it was immediately used to reinforce the Carthaginian forces in Italy with soldiers, supplies and war elephants. It was the only time during the war that Carthage reinforced Hannibal. A second force, under Hannibal's youngest brother Mago, was meant to land in Italy in 215BC but was diverted to Iberia after the Carthaginian defeat there at the battle of Dertosa. Meanwhile, the Romans took drastic steps to raise new legions: enrolling slaves, criminals and those who did not meet the usual property qualification. By early 215BC they were fielding at least 12 legions; by 214BC, 18; and by 213BC, 22. By 212BC the full complement of the legions deployed would have been in excess of 100,000 men, plus, as always, a similar number of allied troops. The majority were deployed in southern Italy in field armies of approximately 20,000 men each. This was insufficient to