The Battle of Cannae

by Scipii

The battle of Cannae is arguably the finest point of Hannibal’s campaign against the Roman Republic during the Second Punic Wars. Not only did he manage to inflict heavily casualties on the eight legions present at the battle but achieved something thought impossible by encircling an army much larger then his own. In this article I will be examining the events leading up to, and during, the battle of Cannae.

After the end of Quintus Fabius Maximus’ tenure as dictator in December 217 BC the Republic held elections to decide who the Consuls for the forthcoming year (216 BC) would be. The minor victory achieved by Marcus Minucius Rufus, who was in command while Fabius was in Rome, in a skirmish against Hannibal’s forces near Gerunium saw support grow for the return of an offensive strategy. The repercussions of this minor victory were to be felt hard by the supporters of Fabius.

The elections for 216 BC saw the balance of power in the Senate sway further to the Aemilii\\Scipionic faction, who were strong advocates of pursuing an offensive strategy against Hannibal. Using their new majority in the Senate the Aemilii\\Scipionic faction reinstated the offensive strategy used by the Republic before the election of Fabius as Dictator. Coinciding with the shift of power to the Aemilii\\Scipionic faction was the election of Lucius Aemilius Paullus and Gaius Terentius Varro, who both supported the proposed offensive strategy against Hannibal, as Consuls.

In a step never taken before in the history of the Republic the Senate decreed that four new legions would be levied to help fight against Hannibal. These new legions were to be commanded by Consuls Paullus and Varro. They would join up with the legions at Gerunium still under the command of Gnaeus Servilius Geminus and Marcus Atilius Regulus (the Consuls for 217 BC, Regulus replacing the deceased Gaius Flaminius Nepos). However, with Hannibal breaking camp in early June under their own initiative Geminius and Regulus decided to follow Hannibal at a safe distance.

Despite provisions by Fabius to procure food supplies from outside of Italy the ruined citadel at Cannae was still an important storehouse for Roman army. In a bid to get the Romans to commit to another pitched battle Hannibal travelled straight from Gerunium to Cannae. Approximately two days march from Cannae the legions of Paullus and Varro finally met up with Geminus and Regulus, who commanded the bulk of the Roman forces, and continued marching together towards Cannae to face Hannibal in a pitched battle.

The ancient historian Polybius states that on the second day of marching (after meeting up with Geminus and Regulus) on July the 29th 216 BC the legions finally spotted Hannibal’s camp about five miles away. The exact location of Hannibal’s camp has been the subject of debate by historians, but one possible candidate is the town of San Ferdinando di Puglia. Depending on who you believe, either Varro or Paullus broke camp in the aim of establishing two new camps on both sides of the river Aufidius positioned closer to Hannibal. The establishment of these two new camps, the larger positioned on the northern bank of the river, was in effect to disrupt Hannibal’s foraging parties forcing him to agree to battle on the terms of Paullus and Varro.

The battlefield at Cannae was chosen carefully and deliberately by Paullus and Varro to minimise the advantages of Hannibal’s cavalry. The river Aufidius prevented Hannibal’s Spanish and Celtic cavalry from outmanoeuvring the Roman legions on their right flank. While on the left flank the Allied cavalry under Varro’s command were protected from outmanoeuvring due to being positioned on the base of the nearby hills. The only option available to Hannibal would be to commit a head on charge in to the opposing cavalry of Paullus and Varro.

Throughout the Second Punic War the Socii (allies of Rome) were expected to provide three horsemen for every two the Romans levied. For every infantryman that Rome levied her Italian allies were expected to provide the same number. The Italian allies, which Hannibal was so desperate to deprive the Republic of, fought the same way as the Roman legions and like Roman citizens bought their own equipment. Often the legionary infantry of the Socii would be positioned on the flanks of the army with the Roman legions stationed in the centre of the line.

On August the 1st camp was broken by Hannibal as he crossed to the southern bank of the river Aufidius in an attempt to offer battle to Paullus and Varro. It was not until August the 2nd that the legions stationed on the northern bank of the river crossed over to the southern bank to join their comrades. Some 10,000 soldiers, quite possibly the Triarii due to their numbers, were left behind to guard the main camp on the northern bank of the river. The decision had been made to engage Hannibal in battle on the fields of Cannae.

While several historians acknowledge Varro as the appointed commander for August the 2nd 216 BC there has been debate as to whether or not this is true. Due to discrepancies some historians now believe that Paullus was actually in command of the legions on the day of the battle. It was he who took up the role of leading the Roman cavalry on the right wing, traditionally a spot reserved for the commander of the legions. The fact that Polybius attributes the pitching of the two camps closer to Hannibal’s position down to Paullus when it was Varro who broke camp has led some historians to advance Polybius’ timetable ahead one day. Using this theory it would be Paullus, a family member of the Aemilii faction, who was in command on the day of the battle and not Varro.

While the number of troops deployed to the battlefield of Cannae by Rome was unprecedented the strategy devised to defeat Hannibal was relatively similar to those before it. Encouraged by the performances of the two surviving Roman legions from the Battle of the River Trebia, who managed to breakthrough the centre of Hannibal’s infantry line, the aim at Cannae was to defeat Hannibal’s infantry using the same method. According to Polybius each maniple of Hastati and Principes was drawn up several times deeper then they were wide. The legions were trading mobility for pure destructive power going forwards, much like a phalanx. However, even with eight legions at their disposal the Romans still lacked the sufficient numbers and quality of cavalry to match that fielded by Hannibal.

In a battle against time the Roman and Allied cavalry would attempt to hold off the might of Hannibal’s cavalry until the legions could defeat Hannibal’s infantry. Like the legions the Roman and Allied cavalry were deployed in a narrow and deep formation. The narrow frontage of the Roman army allowed the legions to fit on to the battlefield. Foremost the deep formation of the Roman and Allied cavalry offered them the best chance of holding out until the legions could achieve their objective.

To counter the strength of Rome’s infantry Hannibal deployed his Gallic and Spanish infantry in a crescent shaped convex formation. Many of the Gallic warriors at Hannibal’s disposal were positioned in the centre of the convex, where the fighting would be the hardest. The centre of the convex would gradually give ground to the advancing legions turning the shape of the formation from a convex in to a concave. The hope was that the legions in their haste to succeed would be sucked in to the space left behind by the retreating centre of Hannibal’s line condensing the formations of the Roman infantry until they could no longer effectively fight. At the right moment the heavy African infantry held in reserve on the flanks behind Hannibal’s Gallic and Spanish infantry would assault the flanks of the legions and pin them in on three sides.

For Hannibal’s strategy to succeed he needed his cavalry to win the day against their counterparts opposite them. On the left flank was positioned the Gallic and Spanish cavalry under the command of Hasdrubal (not Hannibal’s brother) who were expected to route the Roman cavalry opposite them as quickly as possible using all means. On the right flank was the infamous Numidian cavalry under the command of Marhabal who were expected to harass and pin down the Allied Cavalry opposite them led by Varro. Once the legions had been stripped of their supporting cavalry Hasdrubal was to assault the rear of the pinned legions with his Gallic and Spanish cavalry.

The exact numbers and composition of Rome’s army is the subject of much debate. According to Polybius the Romans had at their command approximately 80,000 infantry and 6,000 cavalry. Of the 70,000 infantry which were deployed in the battle of Cannae about 15,000 of them were Velites (Skirmishers) while the remaining 55,000 were of the Hastati and Principes. Despite the poor performance of the Roman cavalry earlier in the war only about 1,600 were deployed on the right flank of the legions. Due to the Socii having to provide at least three Allied horsemen for every two Roman horsemen the Allied cavalry on the left flank numbered about 4,800.

In comparison to the Roman army Polybius states that Hannibal had 40,000 infantry and 10,000 cavalry at his disposal. While Hannibal’s infantry were heavily outnumbered by the Romans his cavalry were clearly superior in quality and numbers. Even less is known about the composition of Hannibal’s army but several plausible suggestions exist.

Mark Healy suggests that ‘nearly one-third of all his infantry were light troops, it has been inferred that the remainder, comprising the phalanx of African heavy infantry numbered about 8,000 men with some 5,500 Spanish troops and about 14,000 Celts making up the rest of the line infantry. Among his cavalry it is estimated that perhaps 4,000 Numidians and 2,000 Spanish remained from his original force with the remaining 4,000 deploying for battle being Celtic heavy cavalry.'[1]

The battle began under a barrage of missiles from the Roman and Carthaginian skirmishers. Soon after the Celtic and Spanish cavalry charged headlong in to the Roman cavalry opposing them. Despite the overwhelming numbers of the Celtic and Spanish cavalry the closed ranks of the Roman cavalry absorbed the shock of the charge. With the momentum of the charge absorbed fierce close quarter combat ensued.

Aemilius Paullus, reportedly wounded by a stone from one of Hannibal’s Balearic slingers, either fell or dismounted from his horse causing the Roman horsemen (believing it to be a signal) to do the same. By dismounting from their horses the Roman cavalry accelerated their own downfall. Unable to effectively hold back the overwhelming number of Celtic and Spanish cavalry opposing them the Roman cavalry were soon cut down, the survivors turning tail routing from the battlefield.

Hasdrubal ordered a detachment of the Celtic and Spanish cavalry under his command to pursue the routing Roman cavalry. Taking the bulk of his cavalry he ordered an assault on the rear of the Allied cavalry securing the left flank of the Roman and Allied legions. Already being harassed by the Numidian cavalry the Allied Cavalry under the command of Varro turned tail and fled at the sight of Hasdrubal and his cavalry. While the Numidian cavalry took off in pursuit of the Allied Cavalry once more Hasdrubal managed to reform his Celtic and Spanish cavalry for one last devastating attack on the Roman army.

Once the Celtic and Spanish cavalry had engaged the Roman cavalry the skirmishers of the Romans and Hannibal disengaged and retreated behind their respective infantry formations. The light troops of Hannibal repositioned themselves to the rear of the African heavy infantry. As the Velites, who had once again performed indifferently despite their numerical superiority, retreated through the massed formation of the legions the Cornicines signaled for the maniples to advance.

The horns of the Cornicen sounded once more ordering the legions to a halt. The Hastati threw their pila at the Celts and Spanish opposing them before unsheathing their swords and charging headlong in to the crescent shaped convex formation of the Celtic and Spanish infantry. The initial momentum of the Roman charge was slowed by the crescent formation of Hannibal’s infantry. Forced to cover more ground in the process of thrusting back the Celtic and Spanish infantry opposite them the legions became further fatigued then usual.

Under relentless pressure from the legions opposing them, who were encouraged by the still living Paullus, the crescent formation of the Celtic and Spanish infantry soon flattened and buckled in to a reversed concave crescent. The Roman legions opposite the unsteady centre of the Celtic and Spanish infantry now eagerly rushed further forwards sensing victory. The swiftly forming salient in the centre of the battle gradually drew more and more maniples away from the outer Roman and Allied legions in towards the centre.

Hannibal’s unhindered African heavy infantry now quickly moved up to assault the exposed flanks of the legions. Unable to combat the threat of the African heavy infantry pinning their flanks the legions faced a renewed assault by the Celtic and Spanish infantry on their front. Already formed in to a narrow dense formation the haste and eagerness at which the legions sought to exploit the wavering centre of Hannibal’s infantry formation saw the Roman formation get even narrower and more condensed. Such was the lack of space in the Roman formation they could not raise their weapons before being cut down by their assailants.

Under assault on three sides the worst was still to come as Hasdrubal and his Celtic and Spanish cavalry charged in to rear of the legions. Encircled the Roman and Allied legions now had no hope of breaking out to survive another day. It is debatable as to whether Polybius or Livy offer the most realistic figures in regards to the dead and captured Romans and Italian allies at Cannae. No matter which figures you believe are correct there can be no debate that at the end of the day the Roman Republic had once more been dealt a crushing blow by Hannibal.

In the aftermath of Cannae the powerful supporter base of the Aemilii\\Scipionic faction disappeared as the Republic once again looked towards Q. Fabius Maximus for salvation. Despite being so close to ruin the peace treaty offered by Hannibal after Cannae was refuted even after the defection of several Italian allies to the south. Regardless of potential manpower shortages six new legions were formed to protect the Republic. Two of these legions were formed from new emergency levies; two more from a small, but sufficient, number of survivors from Cannae; and the last two from bought slaves, criminals and debtors. While many people question why Hannibal did not besiege Rome it is quite possible that he knew he would not be able to take it despite his undeniable talent.


  • Mark Healy, Cannae 216 BC, Osprey Publishing, Printed 1994 (Re-Printed 1996, 1998, 1999, 2000)
  • Joseph Cummins, The War Chronicles: From Chariots To Flintlocks, Allen & Unwin, Printed 2008
  • Livy, The War with Hannibal, Penguin Books, 1965
  • Polybius, The Rise of The Roman Empire, Penguin Books, 2002

[1]Mark Healy, Cannae 216 BC, Osprey Publishing, Printed 1994 (Re-Printed 1996, 1998, 1999, 2000), p76