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
Gelo, son of Hiero II title of king. Livy asserts that, after the huge defeat suffered by the Romans at Cannae, Gelo was preparing to abandon the alliance of Rome for that of Carthage. According to this account, he began making friendly overtures to the cities allied to Rome and might have convinced the entire island of Sicily to defect to the Carthaginian side, had he not died later in the year of 216 BC. However, this seems quite at variance with the statement of Polybius of his uniform submission to his father's views and may very likely deserve as little credit as Livy's insinuation