Battle of Cannae Hannibal at Cannae, with approximately 86,000 Roman and allied troops. They massed their heavy infantry in a deeper formation than usual, while Hannibal used the double-envelopment tactic and surrounded his enemy, trapping the majority of the Roman army, who were then slaughtered. The loss of life on the Roman side was one of the most lethal single day's fighting in history; Adrian Goldsworthy equates the death toll at Cannae to "the massed slaughter of the British Army on the first day of the Somme offensive in 1916." Only about 15,000 Romans, most of whom were from the garrisons of the
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