Editing Second Punic War (section)

=== Roman allies defect, 216–214 BC ===
Little has survived of Polybius's account of Hannibal's army in Italy after Cannae. Livy gives a fuller record, but according to Goldsworthy "his reliability is often suspect", especially with regard to his descriptions of battles; many modern historians agree, but nevertheless his is the best surviving source for this part of the war.{{sfn|Lazenby|1998|p=87}}{{sfn|Goldsworthy|2006|p=222}}{{sfn|Sabin|1996|p=62}}

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 [[Samnium|Samnite]] tribes also joined the Carthaginian cause. By 214{{nbs}}BC the bulk of southern Italy had turned against Rome, although there were many exceptions and 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. They increased the number of places which 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.{{sfn|Goldsworthy|2006|pp=222–226}}

[[File:Second Punic war (cropped).png|thumb|upright=0.85|alt=a map of southern peninsular Italy showing the maximum extent of Carthaginian control|{{center|Hannibal's allies in southern Italy {{circa|213}}{{nbs}}BC, shown in blue}}]]

An important part of Hannibal's campaign in Italy was to attempt to fight the Romans by using local resources; raising recruits from among the local population. His subordinate Hanno was able to raise troops in Samnium in 214 BC, but the Romans intercepted these new levies in the [[Battle of Beneventum (214 BC)|battle of Beneventum]] and eliminated them before they rendezvoused with Hannibal. Hannibal could win allies, but defending them against the Romans was a new and difficult problem, as the Romans could still field multiple armies, which in total greatly outnumbered his own forces.{{sfn|Rawlings|2015|pp=312–316}}

The greatest gain was the second largest city of Italy, Capua, when Hannibal's army marched into [[Campania]] in 216 BC. The inhabitants of Capua held limited Roman citizenship and the aristocracy was linked to the Romans via marriage and friendship, but the possibility of becoming the supreme city of Italy after the evident Roman disasters proved too strong a temptation. The treaty between them and Hannibal can be described as an agreement of friendship, since the Capuans had no obligations.{{sfn|Hoyos|2015b|pp=128–129}} When the port city of [[Locri]] defected to Carthage in the summer of 215{{nbs}}BC it was immediately used to reinforce the Carthaginian forces in Italy with soldiers, supplies and war elephants.{{sfn|Lazenby|1998|p=98}} It was the only time during the war Carthage reinforced Hannibal.{{sfn|Erdkamp|2015|p=75}} A second force, under Hannibal's youngest brother [[Mago Barca|Mago]], was meant to land in Italy in 215{{nbs}}BC but was diverted to Iberia after a major Carthaginian defeat there.{{sfn|Lazenby|1998|p=98}}{{sfn|Barceló|2015|p=370}}

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 215{{nbs}}BC they were fielding at least 12 legions; by 214{{nbs}}BC 18; and by 213{{nbs}}BC 22. By 212 BC 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 challenge Hannibal's army in open battle, but sufficient to force him to concentrate his forces and to hamper his movements.{{sfn|Goldsworthy|2006|pp=226–227}}