Hellenistic period Balkans, Philip allied himself with Carthage after Hannibal had dealt the Romans a massive defeat at the Battle of Cannae (216 BC) during the Second Punic War. Forcing the Romans to fight on another front when they were at a nadir of manpower gained Philip the lasting enmity of the Romans—the only real result from the somewhat insubstantial First Macedonian War (215–202 BC). Once the Second Punic War had been resolved, and the Romans had begun to regather their strength, they looked to re-assert their influence in the Balkans, and to curb the expansion of Philip. A pretext for war
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