I Antiquity · Second Punic War
The perfect pincer: a smaller army surrounds and wipes out another almost twice its size.
Result Decisive victory for Carthage
Background
In the summer of 216 BC, Rome assembled the largest army in its history to finish off Hannibal once and for all. On a plain beside the River Aufidus, the Carthaginian general set for it the most famous trap in military history.
Two years earlier, Hannibal Barca had left Hispania, crossed the Pyrenees and the Alps with his army and his elephants, and carried the war into the heart of Italy. At the Trebia (218 BC) and at Lake Trasimene (217 BC) he destroyed two Roman armies. Rome responded by appointing Quintus Fabius Maximus dictator; he avoided pitched battles and confined himself to wearing down the invader: an effective strategy, but a very unpopular one.
In 216 BC the Senate changed course. The two consuls of the year, Lucius Aemilius Paullus and Gaius Terentius Varro, were given an army of eight legions with their allies. Meanwhile, Hannibal seized the supply depot at Cannae, in Apulia, and drew the Romans onto the plain of the Aufidus, open ground ideal for his cavalry.
The consuls took turns in command each day. The ancient sources, close to Paullus’s family, present him as prudent and Varro as a reckless man who forced the battle. Many historians now believe that the decision to fight was shared by the Senate and by both consuls.
Order of battle
Select a unit to open its card: who commanded it, how it fought and what part it played in the battle.
Gaius Terentius Varro · Lucius Aemilius Paullus · Gnaeus Servilius Geminus
≈ 86,000 according to Polybius (some 10,000 stayed in the camps)
The largest army Rome had ever assembled: eight legions with their allies, commanded by the two consuls of the year, who took turns in command each day.
Hannibal Barca · Mago Barca · Hasdrubal · Maharbal
≈ 40,000 foot soldiers and 10,000 horsemen
An army of mercenaries and allies of very different origins (Africans, Iberians, Celts, Balearic islanders, Numidians) held together by loyalty to their general.
Foot troops with hardly any protection who fight in open order: they harass the enemy with missile weapons, cover the flanks and pull back before the clash.
Infantry with armour and shield, ready for hand-to-hand fighting. Slow, but very hard to break from the front.
Mounted troops. Their speed lets them outflank and pursue the enemy and strike at the enemy’s flanks and rear.
Foot soldiers who fight in close formation. They are the core of almost every army: they hold the line and decide the clash.
Protected horsemen mounted on strong horses. Their charge can break a line, but they tire quickly and find it hard to regroup.
Fast, lightly protected horsemen. They scout, harass, pursue a fleeing enemy and avoid head-on clashes.
The general and his staff. Orders are given from here; losing it can throw the whole army into disorder.
Generals carry their side’s flag, and the most representative units carry their own. Hover over a flag to see its name.
The thick line marks the front of each unit. Teeth in front of it show stakes, walls or other defences. A double border marks elite troops.
Phase by phase
Schematic map. The exact location of the battlefield, and on which bank of the Aufidus it was fought, is still debated.
Phase 1 of 6: The deployment
Phase I of VI · Dawn
Varro leads the army out of the camps and draws it up with the River Aufidus protecting its right flank. The infantry is packed into a huge, deep block: Rome trusts it will crush the enemy centre by sheer weight.
Hannibal replies with a baffling formation. In the centre he places Gauls and Iberians in a crescent that bulges out towards the Romans. Behind its ends, almost hidden, he places his Libyan veterans. Hasdrubal’s heavy cavalry takes position by the river; the Numidians, on the opposite wing.
According to Livy, a south-easterly wind, the Volturnus, was blowing dust into the Romans’ faces.
Phase II of VI · First hours
The Roman velites and the Carthaginian slingers and light spearmen open the fighting in no man’s land. Stones and javelins fly through the air without either side gaining the upper hand.
According to Livy, in these opening exchanges a sling stone wounds the consul Aemilius Paullus. Even so, he stays on the battlefield.
Phase III of VI · Mid-morning
Hasdrubal launches his heavy cavalry against the Roman horsemen. Boxed in between the river and their own infantry, they have no room to manoeuvre. Polybius tells that many dismounted and fought on foot: a brutal fight that the Romans soon lose.
At the other end, the Numidians harass the allied cavalry without coming to close quarters, keeping it busy.
Meanwhile, the velites withdraw through the line and the great mass of Roman infantry sets off against the crescent.
Phase IV of VI · Midday
The Roman infantry crashes into the crescent. Gauls and Iberians fall back step by step, without breaking, just as Hannibal had planned. The curve is reversed: what bulged out towards the enemy becomes a pocket.
The Romans, convinced that they are winning, surge towards the centre. The soldiers on the sides move inwards, the ranks are squeezed together and the army becomes a packed mass with less and less room to use its weapons.
By the river, the Roman cavalry has been wiped out. Aemilius Paullus, wounded, makes his way to the infantry to keep on fighting.
Phase V of VI · Early afternoon
This is the moment Hannibal was waiting for. The Libyan veterans, untouched on both sides of the pocket, turn inwards and fall on the flanks of the Roman mass. The legionaries, packed together, can hardly turn to face them.
Meanwhile, Hasdrubal has rallied his horsemen and rides behind the whole Roman army to the opposite wing. There he charges the allied cavalry, which until then had been holding out against the Numidians, and catches it between two fires.
Phase VI of VI · Afternoon
The allied cavalry collapses and flees; Varro escapes with it. Hasdrubal leaves the pursuit to the Numidians and hurls his horsemen against the rear of the Roman infantry. The encirclement is complete.
What follows is not a battle but a massacre. Surrounded on all sides and with no room to move, the Romans fall in their thousands until nightfall. Aemilius Paullus dies fighting, along with dozens of senators and former magistrates.
By the end of the day, the largest army Rome had ever assembled had ceased to exist.
Tip: use the ← → arrow keys, select a unit to see its card, and zoom with the buttons or with Ctrl + scroll wheel.
What came next
Cannae was the worst defeat in Rome’s history. And yet Rome did not surrender.
In a single day a huge share of Rome’s men of military age died, along with one of the consuls and, according to Livy, some eighty senators. Several cities of southern Italy, among them Capua, one of the richest in the peninsula, went over to Hannibal’s side.
Hannibal did not march on Rome: he had no siege engines and the city was well defended. Livy tells that his cavalry commander, Maharbal, then reproached him: “You know how to gain a victory, Hannibal: you know not how to use one”.
Rome reacted with astonishing determination. It refused to negotiate, did not pay the ransom for the prisoners, enlisted slaves and boys and went back to the strategy of attrition. Hannibal remained undefeated in Italy for years, but more and more isolated.
Fourteen years later, at Zama (202 BC), Publius Cornelius Scipio, a survivor of Cannae, defeated Hannibal in Africa. Carthage lost the war, its fleet and its empire.
Bar: strength. Colour: casualties, with the same figures as the text for each side (depending on the case, only the dead or also the wounded and prisoners). The hatched or lighter part shows the range between the sources.
According to Polybius, the Gauls fought naked from the waist up, while the Iberians wore white tunics with purple borders.
Livy tells that Mago, Hannibal’s brother, emptied out in the senate of Carthage a heap of gold rings taken from the Roman knights killed at Cannae.
The Numidian horsemen rode without saddle or bridle: they guided the horse with their legs, their voice and a simple rope.
Hannibal’s Libyans fought at Cannae with Roman weapons and armour, gathered in their earlier victories.