The slaughter at Cannae: Rome's worst defeat

The Second Punic War had begun in 218 BC, when Hannibal invaded Italy from his base in Spain.

Hannibal's goal was to conquer Rome, and he had already achieved several major victories against the Roman army. 

The most notable victories were at the Battle of Trebia in 218 BC, and the Battle of Lake Trasimene in 217 BC.

Following a catastrophic defeat at Trasimene, the Roman state needed time to rebuild their forces.

So, they appointed the dictator Quintus Fabius Maximus to delay Hannibal for as long as possible in order to prepare for another battle.

Fabius' strategy was simple: he avoided direct confrontation with Hannibal's army, and instead harassed them with smaller skirmishes and raids.

This strategy was effective in wearing down the Carthaginian troops, but it did not result in any major victories.

As time went on, Fabius' policy became unpopular with Roman leaders who thought that he was too afraid of Hannibal.

Some of Fabius' political enemies started to claim that Fabius was secretly working for Hannibal himself.

This was because Hannibal was able to march his troops throughout Italy, burning and looting Roman farms as he went, without being confronted directly by Roman forces.

Hannibal himself was told about the political divisions in Rome and decided to encourage the rumour that Fabius was on his side. 

He ordered his Carthaginian troops to deliberately devastate all Roman property they found except any owned by Fabius. 

When the people in Rome noticed that Fabius was the only one safe from Hannibal's destruction, it seemed to prove that Fabius was being paid by the Carthaginians to avoid battle.

It wasn't that Roman armies weren't in the area of Hannibal's troops, it's just that Fabius did not directly engage them.

Instead, the Roman forces shadowed the Carthaginian troops' movements to try and wear them down.

However, at one stage, Fabius had a perfect opportunity to trap and attack Hannibal.

During the winter, Hannibal had camped his forces in Campania but had accidentally marched them into a valley and became trapped by the nearby Roman army. 

Realising his mistake, Hannibal quickly devised a solution to save his troops. He gathered around 2000 oxen and tied burning torches to their horns. 

At night, they were herded up the side of the valley where the Romans could see them.

Fabius believed the Carthaginians were escaping and pursued the oxen. While the Romans were distracted, Hannibal quickly marched his men out of the valley to freedom.

When dawn broke, the Romans realised that they had been tricked and they had let a perfect opportunity to defeat Hannibal slip through their hands.

For the people back in the city of Rome, who had suspected that Fabius was in support of Hannibal, the news that the Carthaginians had managed to miraculously escape from certain defeat confirmed their fears.

Finally, the Roman Senate grew impatient with Fabius' cautious tactics, and they elected two new consuls to replace him. 

The two consuls were Lucius Aemilius Paulus and Caius Terentius Varro. They both stated that they would abandon any delaying tactics and seek to meet Hannibal on the battlefield once more.

After his successful escape from entrapment, Hannibal moved east and set up his winter camp at Gerunium, near the town of Cannae.

Cannae was a Roman storage site for grain and other food supplies, which Hannibal used to feed his men over winter.

The loss of the food supplies at Cannae had a direct impact on the city of Rome itself. It had just raised four new legions to fight Hannibal and these men needed to be fed, as well as the citizens in Rome.

With the pressure to resolve the Carthaginian problem sooner rather than later, the new Roman troops marched out to engage Hannibal at Cannae.

Hannibal was a master strategist, and he quickly realized that the two Roman consuls would be looking for a chance to engage him in a major battle.

Hannibal's army was made up of approximately 40,000 men, as well as 10,000 cavalry.

The Roman army, on the other hand, had a force of around 80,000 men and 6,400 cavalry.

In order to offset the disadvantage of infantry numbers, Hannibal devised a clever plan.

He lined his 40,000 infantry in a line, but massed his most experienced Spanish, Gallic and African infantry in the centre of his line, bulging forward. 

This created a crescent-moon shaped line with the middle of the line with the most men projected forward towards the Romans and the thinner ends of the line stretched away from the Romans.  

Hannibal's light and heavy cavalry were stationed on the ends of the battle line.

This formation was intended to absorb the overwhelming momentum of the Roman charge.

The plan was to encourage the Romans to attack the very centre of the Carthaginian line in the hopes of overwhelming them.

However, Hannibal had ordered his men to allow the Romans to gradually push them back.

This strategy required the Carthaginians to maintain control against superior enemy numbers.

Most troops would be overcome by fear and flee in that circumstance, but strong leadership could keep them focused.

To ensure they kept to his plan, Hannibal himself stood in the centre of the line to fight with his men.

The two armies met near the city of Cannae in southeastern Italy on the 2nd of August, 216 BC. The battle unfolded in three stages.

In the first stage, the Roman infantry, as Hannibal predicted, charged directly at the Carthaginian center.

The hand-to-hand combat was fierce, and Hannibal encouraged his men to hold the line as long as they could.

As the Roman infantry kept pushing forward, Hannibal slowly let his line be pushed backwards, which meant that the bulging centre of the crescent gradually inverted, and the edges of the Carthaginian line were now located on the sides of the massed Roman formation.

In the second stage, while the infantry was fighting in the middle, the Carthaginian cavalry on the wings rode past the infantry and attacked the Roman cavalry that was waiting behind their troops. After a short clash, the Roman cavalry fled in defeat.

In the third stage, the Carthaginian cavalry that had driven the Roman cavalry away, returned to the centre of the battlefield and attacked the Roman soldiers from behind.

The Romans were now surrounded on all four sides: the Carthaginian infantry in front and on the flanks, and cavalry at the rear.

With no way to escape and surrounded on all sides, the battle then turned into a systematic slaughter of the trapped Roman army.

The Romans were unable to escape, and more than 44,000 men were killed. Hannibal only lost 6000 in comparison.

Among the dead was the consul, Lucius Aemilius Paulus. This was one of the most crushing defeats in Roman history.

The defeat at Cannae led to significant political upheaval in Rome, including the temporary suspension of some civil rights and the institution of emergency measures to protect the city.

The Roman Senate appointed Marcus Junius Pera as dictator, who took drastic measures to stabilize Rome's defenses and morale.

He began to enlist slaves and criminals into the legions: a desperate measure that indicated the dire state of their military resources.

Unfortunately, the disaster at Cannae led several of Rome's allies in southern Italy to defect to Carthage, which significantly weakening Rome's position in the region.

Of the Roman troops that managed to escape the slaughter at Cannae, one was the young Publius Cornelius Scipio who had saved his father from death at the Battle of Ticinus River against Hannibal.

Being a first-hand witness of the disaster at Cannae drove the young Scipio to find a solution to Rome's military problems. 

The Carthaginian victory at Cannae was a turning point in the Second Punic War. It was now the third successive defeat of Roman forces, and it was clear that meeting Hannibal in open battle was not going to work.

Fabius, who had been criticised for his delaying tactics prior to Cannae, was vindicated by history.

Instead, the Roman Senate decided that the only way to defeat Hannibal would be to take the fight to Africa.

Scipio would go on to learn from Hannibal's own tactics and then use them against him at the Battle of Zama 14 years later.