Battle of Cannae the grandfather of Scipio Aemilianus, the patron of Polybius (one of the main sources of this history). In the spring of 216 BC Hannibal took the initiative and seized the large supply depot at Cannae, in the Apulian plain, placing himself between the Romans and their crucial source of supply. As Polybius noted, the capture of Cannae "caused great commotion in the Roman army; for it was not only the loss of the place and the stores in it that distressed them, but the fact that it commanded the surrounding district". The consuls, resolving to confront Hannibal, marched southward in
Socii to raise a double-strength army of four legions and four "alae" e.g. at the Battle of Cannae in 216 BC, where each Consul commanded an army of about 40,000 men. Polybius states that the Romans and their allies could draw on a grand total of 770,000 men fit to bear arms (of which 70,000 met the property requirement for cavalry) in 225 BC, shortly before the start of the Second Punic War. The Romans reportedly asked their allies for an urgent register of all "men fit to bear arms" for a "tumultus Gallicus". Polybius' subtotals, however, are garbled, as he