In August 216 BC, the Romans suffered a devastating defeat at Cannae. Following their defeats at the River Trebia and Lake Trasimene, the Romans had for a time attempted to isolate Hannibal, resisting direct engagements with the Carthaginian invader. But in 216 BC, the consuls of the day changed strategy: they mustered what became the greatest army Rome had ever fielded – eight legions, instead of the usual four.
On the wide, open plain of Cannae, the two armies finally met. The Romans were confident that their superior numbers would guarantee success. Some argue Rome fielded around 50,000 men to Hannibal’s 35,000, though speculative figures rise to as many as 90,000 Romans and allies facing the Carthaginians’ army of 40,000. In a pitched battle, the Romans were on familiar ground. But they lost. How did it happen?
The Roman advance
Hannibal was confident and prepared for battle. He deployed his Gallic light infantry at the front of his army, concealing his heavier infantry – the veterans of Trebbia and Trasimene – in a long, thin, crescent shape behind. As for the Romans, Varro reverted to the primary Roman stratagem of placing his lightly-armed velites at the head of his army, with the principes behind. On either wing were the supporting cavalry. Altogether in one single block, this force would advance, intending to overwhelm the opposing army with their numbers and mass. The Romans sounded the advance.
At first, everything seemed to be going well for the Romans, as the velites easily overcame the Gallic light infantry and pushed forward. On the flanks however, a rather different outcome was emerging. As the Romans made progress in the centre, the quality of Hannibal’s cavalry – and especially his Numidians – proved too much for their Roman counterparts. Unaware of the cavalry’s collapse, the infantry in the centre continued to advance.
Despite overwhelming numbers, only the first few lines could directly engage the enemy. The rest were blindly pushing others forward, keeping the momentum going. Little did they know that once again Hannibal had anticipated the Roman move. The Romans were leading themselves into a deadly trap.
Overwhelmed by the velites, the centre of the Gallic light infantry crumpled. Yet the Roman success was short-lived. At the sides, the crescent shape adopted by Hannibal’s forces now came into effect. The formations of light infantry essentially resembling big pincers, Carthaginians enclosed the Roman army on its flanks.
At the front, too, the Roman light infantry encountered fresh, fierce resistance as the Gallic light infantry gave way to the elite Carthaginian heavy infantry concealed behind. Very quickly, the tide of battle began to shift.
How did the Romans lose at Cannae?
Surrounded on three sides, the advancing mass of Roman soldiers came to an abrupt halt. The Romans now realised the perilous situation they were in; they had been sucked into a death trap, once again. Standing stock-still, they were now easy targets for the returning Numidian cavalry who prevented the Romans escaping from the rear. There was to be no mercy. Almost none survived.
It is both strange and remarkable to us that the Romans, with two consuls present, alternated command of the army on a daily basis. On the day of the battle it is said Varro was in command. However, this version of events may result from aristocratic prejudice, determined to make a scapegoat of Varro on account of his humble background.
Nevertheless, Varro was one of the few Romans who managed to escape by punching through the weakest part of the Carthaginian line; Paullus wasn’t so lucky. With three defeats under its belt, Rome had finally learnt their lesson never to risk the full strength of their armies against Hannibal again.
Rome within sight
The disaster at Cannae sent a shockwave throughout the Mediterranean. The Roman army in Italy was all but destroyed. Hannibal’s path to Rome was clear. Furthermore, the loyalty of socii states to Rome also began to waver.
Coveting Rome’s status as the pre-eminent city in Italy, Capua persuaded the region of Campania to join Hannibal. At the same time, Philip V of Macedon made an alliance with Hannibal igniting a war with Rome in the east. Meanwhile, Syracuse and the other Greek cities in Sicily defected to Hannibal while many of the Greek cities in southern Italy were also offering the Barcid support. To these factions, Hannibal’s final victory looked all-but assured.
Yet, on the verge of victory, Hannibal froze. Whilst he now had the support and siege equipment capable of besieging Rome, for the first time Hannibal was doubtful of success. If he should fail to capture Rome, those who had just joined him would just as easily abandon him. Their loyalty was dependent on his success.
What is more, most of Italy remained hostile to Hannibal. The Latins, Etruscans and the Umbrians – all had rebuked the Carthaginian general and remained loyal to Rome while many Roman strongholds in southern Italy, cities such as Venusia, Paestum and Nola, also kept faith.
Hannibal made the decision that would decide the fate of his expedition. Instead of taking the risk of laying siege to Rome, Hannibal turned away, determined to cultivate more support. The news wasn’t entirely well received by his generals. Maharbal, Hannibal’s greatest cavalry general and a leading advocate of marching on Rome, would famously say,
You know how to gain a victory, Hannibal: you know not how to use one.
He was soon proved right. Hannibal’s decision not to besiege Rome would come back to haunt him.
Rome was sure to learn lessons from their crushing defeat at Cannae. So scathing had this tragedy been, that it was said everyone in Rome could name either a friend or relative who had perished on that ill-fated battleground. Once again, they adopted the Fabian strategy, realising, with the majority of Italy still loyal to Rome, they could gradually wear down Hannibal and his army.
Hannibal continued to rampage through southern Italy in the meantime, trying to galvanise more support. But each victory reaped fewer and fewer rewards. In 212 BC Hannibal took Tarentum, a city with a long history of hostility to Rome, with help from a pro-Carthaginian faction who staged a coup. In the same year, the Romans in Sicily under Marcellus’ leadership seized Syracuse.
Hannibal under threat
Hannibal’s new allies soon proved more of a burden than an aid. As Rome strengthened, levying large numbers of fresh recruits, the Barcid general found that he was spending more time protecting his allies from the Romans than benefitting from their support. This began to take its toll on his weary army.
The fortress of Nola, a suburb of modern Naples, had remained loyal to Rome. It was a persistent thorn in the side of the Campanian allies and therefore to Hannibal himself. Nola’s harbour also represented a key opportunity for Hannibal to resupply and reinforce his army. Unable to abandon his allies lest they defect back to Rome, and desperate for reinforcements, Hannibal was forced to besiege Nola following his victory at Cannae. For three years his army would surround the city, yet to no avail.
Desperately, Hannibal had sent Hanno, one of his lieutenants, south with Mago to gather sorely-needed reinforcements. Having managed to levy Lucanians and Bruttians, from the toe of Italy, to fight for the Carthaginians, Hanno marched north to unite with Hannibal. Meanwhile, Mago returned to the Carthaginian Senate to request more reinforcements.
Disaster at Beneventum
Yet as Hanno sought to re-join Hannibal disaster struck. At Beneventum in 212 BC, barely thirty miles northeast of Nola, the Romans intercepted and utterly destroyed the reinforcement army.
Starved of fresh troops, Hannibal had no alternative but to forsake the siege. If Nola could keep Hannibal at bay without reinforcements, then surely any attempt to march north and capture Rome would prove similarly futile. Reluctantly, Hannibal abandoned Campania and his northern possessions, retreating to the south.
The Romans were slowly confining Hannibal’s army to southern Italy. Gradually, they re-established control over cities exited by the Carthaginians. Hannibal could never hope to protect them all. One by one they fell to the legions. By 209 BC, Fabius recaptured Tarentum, the last of Hannibal’s major allies in southern Italy. With its fall, Hannibal was now essentially isolated in the toe of Italy. The tide appeared to have turned.