It is said that in the lull before the clash between Rome and Carthage at the Battle of Cannae, Gisgo, a commander in the Carthaginian army, remarked nervously to Hannibal, "Sire, they are more than twice our number!"
Hannibal, fully aware of the seemingly impossible odds arrayed before him, replied, "I noticed that, Gisgo, but I also noticed something that you have apparently overlooked... In that entire army, large as it is, there is not one man named Gisgo."
Hannibal's jest diffused the tension felt by the Carthaginian troops, and soon the Punic lines were erupting in laughter.
Cannae, in southeastern Italy, was the site of Hannibal's greatest victory against the Romans in the Second Punic War. The tactics applied by the Punic general are immortalized as a textbook example of the double envelopment tactic, taught in military academies today.
Hannibal had been pillaging up and down the Italian peninsula, evading Roman troops, and, when engaging them, soundly defeating them through a combination of well-laid ambushes and brilliant use of terrain. Rome finally grew tired of his antics and their strategy of waiting out the assaults. At Cannae Hannibal faced the largest army every fielded by Rome, numbering 80,000 men, and fought on fairly open terrain.
Rome at the time was operating on a dual consul system, in which two Consuls were elected as head of state, to lead on alternating days. The day of the battle, Terentius Varro, an aggressive plebian, was commanding the Roman army. Varro positioned his army so as to threaten Hannibal's supply lines, thus forcing an engagement. The Roman army was positioned with its cavalry on the flanks, and legions in center. The legion's maniple formation was more compact than typical. Varro planned to use this dense, powerful infantry unit to hammer through the Punic center. The Roman right was held by heavy cavalry, and the Roman left was held by light cavalry fielded by Rome's allies. Skirmishers were deployed ahead of the line
The Punic battle lines mirrored Rome's. Carthaginian heavy cavalry was deployed on the left, to face Rome's heavy cavalry on the Roman right. Numidian light cavalry, mercenaries hired by Carthage, held the Punic right, facing Roman light cavalry on the Roman left. The Punic center was held by infantry. However, the infantry was deployed in a "bow" formation, rather than a straight line. From above, it would have looked like a large bulge, arcing away from Punic lines towards the Romans
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==: Heavy Cavalry
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When the two lines clashed, Hannibal's cavalry soon demonstrated that Rome's horse was far outclassed. Roman heavy cavalry, relatively inexperienced recruits, were quickly unhorsed and forced to retreat. On the Roman left, the Numidians demonstrated why they had earned a reputation as the greatest light cavalry in the world, outflanking their enemies with lightning maneuvers and routing them.
Meanwhile in the Roman center, the densely packed legions assaulted the Punic center. As Varro foresaw, the Punic center gave way to the might and superior number of the Roman legions. The center and front end the of the bow began to withdraw, until it straightened out, then bent in the other direction. The two ends of the bow, however, remained in position, creating a concave receptacle in the Punic battle lines. The legions charged forward into the center to press their advantage, growing even more densely packed and they flowed into this bulge in the Punic lines.
Then, the Carthaginian heavy cavalry attacked. The Numidians had been tasked with pursuing the fleeing elements of Rome's cavalry. The heavy cavalry, regrouped and heralded by the triumphant sound of war trumpets, fell upon the Roman rear. The legions, facing infantry at their front and sides and cavalry at their rear, were too compact to fight effectively and were slaughtered.
In the final tally, the Romans lost 65,000 of their number, not counting the captured. Carthage lost less than 7,000. It was a devastating defeat for the Romans, and is recorded as the bloodiest single day of battle in history.