The Battle of Cannae

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The Battle of Cannae was fought two years into the war between Rome and her Italian allies on one hand and Carthage and a loose alliance of Gauls and Italian cities on the other.

There are not many ancient battles that have achieved the same scale of fame that the battle between Hannibal and the Roman Consuls Varro and Paulus has. Thermopylae, Marathon, Agincourt, Gettysburg, Waterloo, and Stalingrad are all famous, but mention Cannae to any military history enthusiast and they will immediately light up.

Notable points on the Battle of Cannae

  • The death toll inflicted on the Roman and allied soldiers is equated by scholars to the appalling losses suffered by the British on the first day of the Battle of the Somme in 1916

  • The double envelopment tactic used to, not just defeat the Romans, but to inflict such heavy casualties on them has been widely studied by military historians and is taught in military colleges across the world to this day.

  • Despite the resounding victory, Hannibal and Carthage went on to lose the war.

Prelude

  • Armies: Roman and Italian versus African, Libyan, Spanish, Gallic, and Italian

  • Generals: Hannibal Barca, Mago, Gisgo, Hanno, Maharbal versus Consuls Gaius Terentius Varro and Lucius Aemilius Paulus

  • Location: The plains of Cannae

  • Season: Spring of 216BC

  • Weather: Hot and windy

Rome

After a series of humiliating and morale-sapping defeats, the Roman Senate was desperate for a decisive victory over Hannibal. To that end, they had raised 40,000 Romans soldiers, supplemented by an equal number of Auxiliaries from among their Italian neighbors. The vast majority of the Roman and Italians were fresh recruits with little military experience and no combat experience.

This extraordinarily large army was led by two Consuls with very different outlooks and to compound this, command of the army alternated between them daily. The consul Varro vowed over and over to destroy the enemy the day they met in battle while his fellow consul, Paulus promised to do what was necessary according to circumstances on the day. Wary of Varro’s bluster, Quintus Fabius Maximus, who firmly believed Hannibal should be defeated by attrition rather than direct confrontation, pleaded with Paulus to exercise caution to avoid another defeat like that inflicted at Lake Trasimene.

Before the newly raised Roman and allied legions marched from Rome, the decemviri had to inspect the sacred volumes due to reports of omens which had spooked the soldiers;

  • It had rained stones on the Aventine in Rome and at Aricia at the same time.

  • Among the Sabines, statues had sweated blood copiously,

  • At Caere, a fountain had spewed warm water.

  • In a street called the Arched Way, near the Campus Martius, several men were struck by lightning and killed.

Only once the omens were explained away according to the sacred books, could the legions could march forth with renewed confidence.

Livy, Book XXI, Pg 76

It was normal for soldiers to make vows to fight for each other prior to a battle. Now, for the first time, these usual military pacts were made official when both Roman and allied soldiers were ordered by their Tribunes to give their oath that they would, “not depart or quit their ranks for flight or fear, except for the purpose of taking up or fetching a weapon, and either striking an enemy or saving a countryman.”

Fighting Units

The senate doubled the standard number of legions from four to eight and increased the legions' strength to 5,000 legionaries and 300 horsemen.

An equal number of Auxiliary soldiers were raised along with 4,800 horsemen.

In total, the Romans fielded an army of over 87,000 men.

Roman arms and armour

Roman foot soldiers were equipped with their favoured pila, the iconic Roman javelin. They would also have the heavier thrusting spears or hastae.

Every soldier was also armed with a sword which at that time was longer than the gladius that evolved from the Hispanic short sword and became the preferred personal weapon of legionaries.

The men wore square chest plates for body armour and bronze helmets to protect their heads. Wealthy soldiers usually rode as equites, but those that fought in the maniples might have worn mail coats reinforced at the shoulders.

Hannibal Barca

Fabius’ advice to Paulus included the truth about the lack of provisions among Hannibal’s army. They had been forced to plunder the countryside for food, but much of the harvest had been collected into the fortified cities. When the battle was fought, Hannibal’s army had rations for just 10 days and there was concern that the Spanish warriors would cross to the Romans.

Provisions aside, Hannibal had the advantage of a cohort of highly experienced officers using an established communication system to command a veteran army. He was able to rely implicitly on Mago, his younger brother, Hasdrubal, Hanno, and Maharbal to control his 40,000 warriors and 10,000 horsemen.

Upon the arrival of the Roman army with its accompanying wagons of provisions, Hannibal is said to have rejoiced, certain that his army would eat again once the battle had been fought.

Weapons and armour

These varied widely due to the huge numbers of mercenary contingents from Africa, the Near East, the Cisalpine, and Iberia.

 

Foot soldiers

Hannibal’s approximate 8,000 skirmishers included slingers, archers, and mixed javelin throwers.

His foot soldiers were drawn from numerous nations. The most experienced heavy infantry were the Libyans, Africans and Iberians. The Gauls with practically no armour and poor-quality slashing swords, made up the bulk of his light infantry or pilum-fodder.

The Iberians used stabbing swords which the Romans later adopted as their gladius. Wealthier Iberians were armed with a notoriously lethal hacking blade called a falcata. Their armour was primarily bronze chest plates and regular bronze helmets. They used large oval shields for defence.

The regular Gallic warriors wielded long slashing swords whose blades were prone to bending and twisting. Their armour was sparse and most fought barefoot and bare-chested, relying on their large shields to divert missiles and blades. The wealthier Gallic nobles and champions were far better equipped with mail armour and bronze helmets.

It is unclear what arms and armour the Libyans traditionally fought with. Polybius writes that the Libyans used captured Roman equipment. Considering how they were deployed, it is apparent they were heavily armed and armoured and it is likely they fought with spears, swords, or both.

Horsemen

The Numidian light horsemen relied on speed and agility in attack and carried only a quiver of javelins and a small circular shield. Excellent horsemen, they used no saddles or even reins.

The heavier Iberian horsemen used circular shields known as caetra for defence and fought with javelins, lances and swords. They preferred to fight on foot and use their horses instead to get them and a passenger or two to where they were needed in battle.

The Gallic horsemen were also a heavy cavalry and fought with shields, spears, and swords. Again, the wealthier of them were much better equipped with mail coats and bronze helmets.

Skirmishers

The Balearic slingers were highly sought after as skirmishers due to their accuracy and speed. Trained from an early age to hunt for food, they grew up to make a living as mercenaries in wars all around the Mediterranean.

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Opening manoeuvres

In the Spring of 216 BC, Hannibal crossed the River Aufidius and occupied the town of Cannae, a strategic Roman grain depot. In occupying Cannae, Hannibal both secured much needed provisions for his army and endangered Rome's supplies. The town overlooked a broad plain, bisected by the river. The ideal terrain to manoeuvre his 10,000 horsemen was the wider western plain.

Pursuing Hannibal’s army, the Romans arrived on the plain beneath the town of Cannae. Paulus favoured the hillier, more broken eastern plain, believing it would give the Roman army an advantage against Hannibal’s lethal Iberian and Numidian cavalry. Varro insisted on drawing up on the western plain, eager for the enemy army to engage. The Romans and their allies prepared their battle formations two miles from Hannibal’s lines.

In an attempt to lure the Romans to battle on the broader Western plain, Hannibal sent his Numidians to skirmish and harass the smaller Roman camp on the Western bank. They attacked right up to the gates of the camp, terrifying the Romans.

On the morning of the battle, Varro reassessed his position and opted to cross to the Eastern bank of the river where he drew up his lines. The Roman cavalry took up a position on the river, the right wing. The Roman legions formed their lines in the centre with the allied foot soldiers on their left and the allied cavalry holding the left wing. Varro commanded the left wing, Paulus the right and the previous year’s Consul, Gnaeus Servilius Geminus, the centre. To the front went all the skirmishers, the slingers, javelin throwers and archers.

Hannibal quickly reacted to the Roman deployment by sending his skirmishers across to the river. His Gallic and Iberian cavalry followed to hold the flank closest to the river, facing the Roman cavalry. His Numidians swung wide to face the allied horsemen on Hannibal’s left flank. The foot soldiers took the centre of the lines, the Gauls and Iberians in the centre, with the Africans either flank. Hasdrubal took command of the left flank, Maharbal the right and Hannibal the centre. Now Hannibal adjusted the centre of his lines by moving the Gauls and Iberians forward until the whole line formed a convex shape and was thinnest at the very centre.

Hannibal’s army had the wind at their backs and at that time of year it was full of dust which would have been a factor in hampering the Romans’ sight.

Tactics

With the armies in their respective battle formations, the initial fighting began with the opposing skirmishers advancing. Young, inexperienced Romans would have gone forward to hurl pila at the enemy skirmishers. Archers from Syracuse targeted their counterparts from Iberia and Balearic slingers picked off Rome’s Italian allies and one man, targeted and struck Paulus, the Roman Consul commanding the Roman’s right flank.

As the skirmishers vied for control of the field, Hasdrubal raised his sword and signalled to the Iberian and Gallic horsemen to advance at a walk before breaking into a canter and then a full charge. Their sights set on the Roman cavalry, they let loose their war cries. In response, the Roman horse was forced to charge headlong toward Hannibal’s heavy cavalry, hemmed in by the river and their own legionaries. The first waves collided and very soon the fight slid from on horseback to on foot. It was a brief, violent battle that did not last long before the Roman cavalry buckled and began to flee.

On Hannibal’s right flank, a band of five hundred Numidians broke away from the African cavalry and raced to the Roman’s allied cavalry where they leapt from their ponies, throwing aside shields and javelins in surrender. Varro ordered them to be escorted to the rear lines where they remained until the Roman allied cavalry was fully committed to battle with the bulk of the Numidian horsemen.

While the Roman and Auxiliary cavalry were engaging on the flanks, the Roman and allied legionaries advanced, their eyes on those of the grizzled Iberian and Gallic warriors. Their front ranks drove into the enemy with a might clash and the Battle of Cannae began in earnest. The Iberians with their stabbing blades and large shields were equal to anything the Romans could offer and held firm. The Gauls fought beside their Iberian allies with determination, their broad shoulders swinging their long hacking swords into the Romans, exacting a toll on the inexperienced legionaries.

Then the full force of the Numidian horsemen charged the auxiliary cavalry and while they were still reeling under a storm of lethal javelins, Hasdrubal led the Iberian and Gallic heavy cavalry across the battlefield to hit them in the flank. The five hundred Numidians who had appeared to have exchanged sides, turned, and regaining their ponies, attacked the allied cavalry from the rear. Beset on all sides, hamstrung and speared through, it was only a matter of heartbeats before the allied cavalry was overwhelmed. In the midst of the carnage, Consul Varro and seventy riders managed to break out of the melee and flee the field.

Despite their strength and valour, Hannibal’s Iberian and Gallic lines proved too thin for the massed Roman formations who began to drive them back. Once on the back foot, the Gauls and Iberians fell back faster and faster. Sensing victory, the Romans cheered and pushed forward into the flying dust storm, eager to crush the enemy at last. In a brief respite from the wind, the air cleared to reveal Hannibal’s African formations curling around to encircle them. As the Africans sprung the envelopment, the Iberians and Gauls regrouped, baying for Roman blood. Surrounded, the battle-weary legionaries’ numerical superiority was nullified, and they were at the mercy of Hannibal’s veterans.

On the Roman right, the injured Paulus had rallied the Roman cavalry against Hannibal’s Iberian and Gallic horsemen time and again. Finally, the wound sustained from a slingshot and the exertion of battle overtake him and he falls from his mount. The Roman cavalry, forced to fight on foot, finally lose all cohesion and men begin to flee. As a Roman Tribune, Cneius Lentulus, escaped the field of slaughter, he saw the blood-soaked Consul Paulus sitting on a rock and tried to convince him to flee. The Consul is unable to and moments later, the enemy overrun the position and Paulus falls beneath their blades.

The outcome of the battle was in no doubt at this point, but for the thousands of Romans encircled, the day would only end when an Iberian falcata took their head or a Gallic sword opened their throat.

Aftermath

“Aemilius Paulus and Terentius Varro are routed at Cannae, and forty thousand men slain, among whom were Paulus the consul, eighty senators, and thirty who had served the office of consul, praetor, or edile. A design projected by some noble youths of quitting Italy in despair after this calamity, is intrepidly quashed by Publius Cornelius Scipio, a military tribune, afterwards surnamed Africanus.”

Livy Book XXI

The death toll among Roman and allied soldiers was staggering. Livy puts the numbers killed at 42,700 soldiers and horsemen. 7,000 escaped to the small encampment on the western plain while 10,000 fled back to a larger encampment two miles to the north. 2,000 men fled into the town of Cannae, but it had no walls and they were quickly surrounded by horsemen and captured along with a further 1,000 survivors from the battlefield.

The number of senior officers, senators and nobles killed in the battle was astonishing and a further severe blow to Rome.

Those who fled to the smaller encampment later attempted to break through the jubilant enemy to reach their comrades in the larger encampment across the river. The Numidians had been expecting them to try this and just 600 men made it across the river. From there, the 10,000 survivors made their way to Canusium.

The outcome of the battle

Rome was horrified at the scale of the defeat, so much so that they resorted to human sacrifice; burying alive people in the Forum and casting a baby into the sea.

The defeat resounded across Southern Italia and the Hellenistic southern provinces of Arpi, Salapia, Herdonia, Uzentum, including the cities of Capua and Tarentum (two of the largest city-states in Italy) pledged their support for Hannibal Barca. The Greek cities in Sicily were induced to revolt against Rome and the Macedonian king, Philip V, pledged his support to Hannibal, initiating the First Macedonian War against Rome. Hannibal also secured an alliance with the new King Hieronymus of Syracuse, the only independent king left in Sicily.

Mago took the news of the victory to Carthage, detailing the numbers of Romans killed and captured, and the cities that now supported Hannibal. He is said to have underscored the victory at Cannae by spilling a chest full of golden rings across the senate floor. These were the rings of Romans who had earned them through exceptional bravery and who had been slain in battle by Hannibal’s army. The point of the display was to convince the Carthaginian senate to raise funds for reinforcements for Hannibal’s army and it was successful. Mago was permitted to raise 12,000 foot soldiers, 1,500 cavalry, and a further 20 elephants.

Hopeful that the defeat would sway them, Hannibal sent Carthalo to negotiate a peace treaty with the Roman Senate. However, they refused outright to negotiate, refusing even to pay ransom for those Romans that were captured.

The much-needed reinforcements raised by Mago never arrived, having been forced to reroute to Iberia to secure that territory of after Hasdrubal Barca’s defeat at the Dertosa in the spring of 215 BC.

And so, despite achieving a resounding victory, Hannibal was never able to fully capitalise on the victory.

The double envelopment tactic

A general achieves a double envelopment when his army encircles an attacking force by outflanking it on both sides and consolidating a position on all the attacker’s fronts. The two most likely outcomes for the encircled force is to surrender or be destroyed.

 

References:

Author J. Glenn Bauer

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