Battle of Cannae (216 BC): Hannibal's Masterpiece of Encirclement

The Battle of Cannae, fought on 2 August 216 BC near the town of Cannae in Apulia, southern Italy, was Hannibal’s greatest victory over Rome. With a smaller army, he drew the massed Roman legions into his centre, closed both flanks with his African infantry and sealed the rear with his cavalry, encircling and destroying the largest army Rome had yet put into the field. Cannae became the textbook example of the double envelopment and is still studied as one of the most complete victories in military history.

Background

Hannibal had invaded Italy in 218 BC and won crushing victories at the Trebia and at Lake Trasimene. In 217 BC the dictator Quintus Fabius Maximus had followed a cautious policy of avoiding battle, known as the Fabian strategy. It saved the Roman army but was deeply unpopular while Hannibal ravaged Italian farmland.

For 216 BC Rome elected two new consuls, Lucius Aemilius Paullus, an experienced aristocrat, and Gaius Terentius Varro, a politician of more modest origins. The Senate decided to seek a decisive battle and raised an army of unprecedented size: eight legions, each apparently enlarged, together with an equal or greater number of allied troops.

Causes and the road to battle

In early summer 216 BC Hannibal seized the Roman supply depot at Cannae, a small hilltop town above the river Aufidus (Ofanto) near the Adriatic coast. The move cut the Romans off from important supplies in Apulia and placed Hannibal on open, flat ground well suited to his cavalry.

The consuls followed him with their combined army. By Roman custom, two consuls with a joint army commanded on alternate days. Ancient writers, especially Livy, portray Paullus as cautious and Varro as reckless. Many modern historians think this picture is unfair to Varro and reflects the later influence of Paullus’s family, and that the Senate as a whole wanted a battle.

After some days of manoeuvre and a skirmish, the Romans crossed the river and drew up for battle on a day when Varro held command, 2 August 216 BC according to the Roman calendar.

The armies

Polybius says the Roman army numbered about 80,000 infantry and a little over 6,000 cavalry, of whom about 10,000 were left to guard the camps. Livy notes that ancient writers disagreed about the total. Modern estimates of the Romans and allies actually on the field range from about 50,000 to 80,000, with many historians favouring a figure in the region of 70,000 men or somewhat fewer.

Hannibal had about 40,000 infantry and 10,000 cavalry. His infantry included Gauls, Iberians and the veteran Libyan foot soldiers from Africa, many of whom now carried captured Roman equipment. His cavalry, Iberian and Gallic heavy horse and Numidian light horse, was superior to the Roman cavalry in both numbers and experience.

The battle

The Romans deployed their infantry in an unusually deep and narrow formation, hoping to smash through the Carthaginian centre by sheer weight. Roman citizen cavalry stood on the right wing by the river, the allied cavalry on the left.

Hannibal placed his Gallic and Iberian infantry in the centre, pushed forward in a crescent bulging towards the enemy. Behind them on each side, out of the main line, stood a deep body of Libyan infantry. On his left, by the river, he put his heavy cavalry under an officer named Hasdrubal; on the right, the Numidian horse.

The battle began with fierce fighting between the cavalry. On the river side, in a cramped space, Hasdrubal’s horsemen overwhelmed the Roman cavalry and cut most of them down. Hasdrubal then rode behind the Roman army to help the Numidians, who had been skirmishing with the allied cavalry on the other flank, and together they drove the allied horse from the field.

Meanwhile the Roman infantry pressed forward against the Carthaginian centre. The crescent slowly bent back and then became a hollow, drawing the Romans deeper and deeper into a pocket. As the legions crowded forward, the Libyan infantry on both sides turned inward and attacked their flanks. Hasdrubal’s cavalry then returned from the pursuit and struck the Roman rear.

The Roman army was now enclosed on all sides. Packed so tightly that many men could not use their weapons, the soldiers were slaughtered over the rest of the day. Paullus was killed; Varro escaped with some cavalry to Venusia.

Casualties

The death toll at Cannae is one of the most debated figures in ancient history.

Polybius says that only about 3,000 Roman infantry escaped from the battlefield itself. Modern historians usually place the Roman dead somewhere between Livy’s and Polybius’s figures, often around 50,000. Among the dead were the consul Paullus, the former consuls Gnaeus Servilius Geminus and Marcus Minucius Rufus, and, according to Livy, 80 men of senatorial rank. Whatever the exact number, Cannae was one of the bloodiest single days of fighting in history before the modern era.

Aftermath

Livy reports that the cavalry commander Maharbal urged Hannibal to march on Rome at once and, when he refused, told him that he knew how to win a victory but not how to use one. Hannibal, without siege equipment and far from reinforcements, instead hoped that Rome’s allies would desert it and that Rome would negotiate. He even sent a delegation to discuss the ransom of prisoners, but the Senate refused to receive it.

In Carthage, Livy says, Hannibal’s brother Mago reported the victory to the senate and poured out on the floor a heap of gold rings taken from dead Roman knights and senators. Livy notes that accounts of the quantity varied, the most cautious putting it at about one Roman modius, a measure of roughly nine litres.

The political effects were serious. Capua, the second city of Italy, went over to Hannibal, followed by many communities in Apulia, Samnium, Lucania and Bruttium. In 215 BC Philip V of Macedon made an alliance with Carthage, and after the death of King Hiero II, Syracuse also broke with Rome.

Rome’s response showed its extraordinary resilience. It refused to ransom its captured soldiers and raised new legions, including two of slave volunteers, the volones, promised freedom for service. Livy records that in the panic the Romans also carried out a rare human sacrifice, burying a Gallic and a Greek couple alive in the Forum Boarium. The survivors of Cannae were formed into the “Cannae legions” and sent to Sicily in disgrace, where they served for years without leave; many later fought under Scipio in Africa.

Crucially, the core of Rome’s alliance in central Italy, the Latin colonies and most of the allies of Latium, Etruria and Umbria, stayed loyal. Rome returned to a cautious strategy, avoided battle with Hannibal and slowly recovered the rebel cities.

Key people

• Hannibal Barca: Carthaginian commander, who designed the encirclement.
• Lucius Aemilius Paullus: Roman consul, killed in the battle. His son was the victor of Pydna in 168 BC.
• Gaius Terentius Varro: Roman consul in command on the day, who survived and was later thanked by the Senate for “not despairing of the Republic”.
• Hasdrubal: commander of Hannibal’s heavy cavalry (not his brother), whose charge decided the battle.
• Maharbal: Carthaginian cavalry officer, remembered for urging an immediate march on Rome.

Legacy

Cannae has become a byword for the perfect battle of annihilation. In the early 20th century the former German chief of staff Alfred von Schlieffen wrote a series of studies under the title “Cannae”, using it as a model for encircling and destroying an enemy army. German officers saw their encirclement of the Russian Second Army at the Battle of Tannenberg in 1914 as a modern Cannae, and the term is still used for battles of encirclement.

Yet Cannae is also a lesson in the limits of battlefield victory. Hannibal never won the war. Rome’s manpower, political cohesion and refusal to negotiate turned a catastrophic defeat into a long war of attrition, which ended with Scipio’s victory over Hannibal at Zama in 202 BC.

Timeline

• 217 BC: Hannibal defeats the Romans at Lake Trasimene; Fabius Maximus is dictator.
• 216 BC, March: Paullus and Varro take office as consuls.
• 216 BC, early summer: Hannibal captures the Roman supply depot at Cannae.
• 216 BC, 2 August (Roman calendar): Battle of Cannae.
• 216 BC, late summer and autumn: Capua and many southern Italian communities defect to Hannibal.
• 215 BC: Philip V of Macedon allies with Carthage.
• 211 BC: Rome recaptures Capua.

Why it matters

Cannae was the high point of Hannibal’s war in Italy and one of the most complete tactical victories ever won. It shook Rome’s alliance system to its foundations, yet Rome’s survival afterwards showed the strength of its institutions. For more than two thousand years, soldiers have studied the battle as the model of the encirclement.