I am currently working on a new series about the Second Punic War (218-201 BCE). This is a lot of work and it is taking up much of my spare time. I will therefore repost a ‘golden oldie’, a post I wrote many years ago for an internet forum. The post was a contribution to a thread about great gambles in military history and I decided to discuss Hannibal’s invasion of Italy and especially his victory at Cannae in 216 BCE. I have made a few changes to the text below, the original of which can be found here.
Hannibal’s invasion of Italy was a great gamble, and the Battle of Cannae, though obviously his greatest victory, was also Hannibal’s greatest gamble. Having just read Adrian Goldsworthy’s detailed analysis of the battle, I can safely say that the Romans were actually an inch away from winning that battle. The whole Italian campaign was extremely risky to start with. Hannibal had to take an enormous army (sources say close to 100.000 men, but that may be an exaggeration) over the Pyrenees and the Alps, through hostile territories, past savage and independent mountain tribes and through awful weather. After the crossing of the Alps, only a quarter of Hannibal’s army was still there. Thousands had died or deserted and the Carthaginian and his 26.000 men now had to win the hearts and minds of the Celtic tribes that had recently been defeated by the Romans. Certainly, those tribes felt no great love for Rome, but it was far from certain that they would join Hannibal’s cause, as they knew full well what it meant to incur the wrath of Rome. Another element in Hannibal’s big gamble.
Ultimately some 20.000 Celts joined Hannibal’s seasoned army and together they would smash Roman armies at Ticinus, Trebia and Lake Trasimene. The Romans then responded by trying a strategy of avoiding battle: Quintus Fabius, later nicknamed ‘Cunctator’ , ‘the Delayer’, was appointed as dictator and made sure that his troops harassed Hannibal’s army as much as possible without actually engaging in a pitched battle. This strategy was deeply unpopular, and in the summer of 216 BCE, the Romans had formed one of the largest armies ever assembled in the history of the Roman Republic. Some 80.000 infantry (8 legions + 8 allied alae) and 6.000 cavalry were sent after Hannibal who, having largely failed to persuade Rome’s Italian allies to join him, was now moving through Southern Italy mostly unopposed.
On 2 August 216 BCE, the Roman consul Varro offered battle near the town of Cannae. Although the exact location of the battlefield is uncertain and many sites have been proposed, Goldsworthy assumes the battle took place between the river Aufidus and the hills near Cannae. This terrain clearly favoured the Romans, as it would be difficult for the Carthaginians to flank the Roman army. Facing the river on their left and the rocky terrain on their right, the Spanish, Celtic and Numidian horsemen in Hannibal’s army had no opportunity to simply ride around the Roman flanks. Although it is certain that the Romans did not deploy all of their 86.000 men – some 10.000 were left behind to guard the camps – it was quite clear that the Carthaginians were outnumbered. Hannibal took a huge risk by placing the weaker Iberians and Celts in the centre and advancing his centre so that the Carthaginian battle line had the shape of a crescent. His best troops, the North Africans (‘Libyans’ in our sources), were equipped with spoils of war taken from slain Roman soldiers and they were positioned on the flanks, most likely in a column somewhat behind the Iberians and Celts, so that the Romans could not see them.
Hannibal took a huge risk by sending the cavalry on his left wing, commanded by Hasdrubal, in an all-out charge against the enemy right flank, but the attack was a complete success and the Roman horse were routed. Still, this was only a minor success, as the Roman centre began pushing back the Celtic and Iberian infantry. These held out long, but ultimately collapsed into rout. The Romans had achieved a breakthrough and began pursuing the fleeing enemy. More and more troops were sucked into the Carthaginian formation and according to Goldsworthy, victory for the Romans was imminent.
Then the North African reserves on both flanks turned inward and stopped the Roman advance. The Romans, already deployed in a slightly unusual formation, with extremely deep maniples placed closely together, were completely taken by surprise. And what was more important: they had become one compact mass of soldiers without any order. Maniple was intermingled with maniple and chaos was compete. The Numidian cavalry on the right wing had been skirmishing with the Italian allied cavalry, but Hasdrubal had reformed his horse on the left and now led an attack against the Italians, who fled almost instantly. The Numidians pursued and Hasdrubal led his horsemen against the Roman rear. Then the great slaughter began. The encircled Romans fought bravely and took a significant number of enemies with them, but it was no good. Some 50.000 Romans died. But Hannibal had suffered appalling casualties too. Some 5.700 of his men lay dead, more than 10% of his army.
Cannae was Hannibal’s greatest victory, but also his greatest gamble. In fact, the whole Italian campaign was a gamble. Hannibal managed to persuade most of Southern Italy to defect to him, but he could not capture large ports and was not given much support from Carthage itself. Carthaginian territory in Spain was threatened by Roman forces and the Carthaginian senate preferred to send aid to the Iberian peninsula instead. Hannibal was unable or unwilling to march on Rome itself. Quite clearly he had expected the city to surrender after such a huge defeat. But it did not. Instead it put new armies in the field and even created a new front in a war with Philippos V of Macedonia. Hannibal was free to move through Southern Italy, but the Romans began to slowly reconquer the cities that had defected, Capua in 211 BCE and Tarentum in 209 BCE. A relief army led by Hannibal’s brother Hasdrubal was soundly defeated at the Metaurus River in 207 BCE, and at the same time the Romans were making significant progress in Spain under a promising young general who had learned much from Hannibal’s tactics and who would even employ some sort of “reverse Cannae” tactic at Ilipa in 206 BCE. This promising young general was Publius Cornelius Scipio, soon to be nicknamed Africanus. When this general landed in North Africa, defeated a Carthaginian army at Great Plains (203 BCE) and threatened Carthage itself, Hannibal was forced to retreat from Italy. His bold plan had failed, even though he was never really beaten on Italian soil.