Battle of Cannae

Rome typically employed four legions each year, each consisting of 4,000 foot soldiers and 200 cavalry.[14] Per contemporary Roman sources, for the first time ever the Senate introduced eight legions, each consisting of 5,000 foot soldiers and 300 cavalry, with allied troops numbering the same number of foot soldiers but 900 cavalry per legion—more than triple the legion numbers.[15] Eight legions—some 40,000 Roman soldiers and an estimated 2,400 cavalry—formed the core of this massive new army.[16] Livy quotes one source stating the Romans added only 10,000 men to their usual army.[17] While no definitive number of Roman troops exists, all sources agree that the Carthaginians faced a considerably larger foe.

Ancient historians rarely provide the precise dates for the events they describe; for example, Livy provides no explicit dates for any of the battles of the Second Punic War. However, Macrobius, citing the Roman annalist Quintus Claudius Quadrigarius, states the battle was fought ante diem iiii nones Sextilis, or 2 August.[29]

The months of the pre-Julian Roman calendar are known not to correspond to its namesake Julian day; for example, Livy records a lunar eclipse in 168 BC as occurring on 4 September, when astronomical calculations show it happened on Julian day 21 June of that year.[30] This discrepancy arose from the failure of the pontifices to properly perform intercalations, either by accident or for political advantage. A review of the evidence led P.S. Derow to identify the equivalent Julian date would be 1 July 216 BC; other authorities have suggested other Julian dates.[31]

Modern interpretation of a slinger from the Balearic Islands (famous for the skill of their slingers)

Figures for troops involved in ancient battles are often unreliable, and Cannae is no exception. They should be treated with caution, especially those for the Carthaginian side.[32] The Carthaginian army was a combination of warriors from numerous regions, and may have numbered between 40,000 and 50,000. Their infantry comprised an estimated 8,000 Libyans, 5,500 Gaetulian, 16,000 Gauls, mainly Boii and Insubres (8,000 were left at camp the day of battle) and 8,000 of several tribes of Hispania, including Iberians, Celtiberians and Lusitanians.[33] Hannibal's cavalry also came from diverse backgrounds. He commanded 4,000 Numidian, 2,000 Iberian peninsular, 4,000 Gallic and 450 Libyan-Phoenician cavalry. Finally, Hannibal had an auxiliary skirmisher contingent consisting of 1,000–2,000 Balearic slingers and 6,000 mixed-nationality javelinmen, possibly including Lusitanians among them.[34] The uniting factor for the Carthaginian army was the personal tie each group had with Hannibal.[35][36]

Rome's forces used typical Roman equipment including pila (heavy javelins) and hastae (thrusting spears) as weapons as well as traditional bronze helmets, bodyshields and body armor.[37] On the other hand, the Carthaginian army used a variety of equipment. The Iberians fought with falcatas, while Celtiberians and Lusitanians would use straight gladii,[38] as well as javelins and various types of spears.[39] For defense, warriors from Hispania carried large oval shields and often wore a crested helmet made of animal sinews.[39] Most Gallic foot warriors likely had no protection other than large shields, and the typical Gallic weapon was a long slashing sword.[40] The Numidian cavalry were very lightly equipped, lacking saddles and bridles for their horses, and wearing no armor but carrying small shields, javelins and possibly a knife or a longer blade.[39] In contrast, the heavier Iberian peninsular cavalry carried round shields, swords, javelins and thrusting spears.[41] The similarly heavy Gallic cavalry added the four-horned saddle, with the wealthier ones being clad in mail, a Gallic invention.[39] Skirmishers acting as light infantry carried either slings or javelins. The Balearic slingers, who were famous for their accuracy, carried short, medium and long slings used to cast stones or bullets. They may have carried a small shield or simple leather pelt on their arms, but this is uncertain. Hannibal himself, like many Roman officers on the opposing side, might have been wearing a bronze musculata and carrying a falcata as his personal sidearm.[42]

The equipment of the Libyan line infantry has been much debated. Duncan Head has argued in favor of short stabbing spears.[43] Polybius states that the Libyans fought with equipment taken from previously defeated Romans. It is unclear whether he meant only shields and armor or offensive weapons as well,[44] though a general reading suggests he meant the whole panoply of arms and armor, and even tactical organization. Apart from his description of the battle itself, when later discussing the subject of the Roman legion versus the Greek phalanx, Polybius says that "...against Hannibal, the defeats they suffered had nothing to do with weapons or formations" because "Hannibal himself... discarded the equipment with which he had started out [and] armed his troops with Roman weapons".[40] Gregory Daly is inclined to the view that Libyan infantry would have copied the Iberian use of the sword during their fighting there and so were armed similarly to the Romans.[45] Peter Connolly has argued that they were armed as a pike phalanx.[46] This has been disputed by Head, because Plutarch states they carried spears shorter than the Roman triarii[43] and by Daly because they could not have carried an unwieldy pike at the same time as a heavy Roman-style shield.[44]

The conventional deployment for armies of the time was placement of infantry in the center, with the cavalry in two flanking wings. The Romans followed this convention fairly closely, but chose extra depth rather than breadth for the infantry in hopes of breaking quickly through the center of Hannibal's line.[47] Varro knew how the Roman infantry had managed to penetrate Hannibal's center at Trebia, and he planned to recreate this on an even greater scale.[48] The principes were stationed immediately behind the hastati, ready to push forward at first contact to ensure the Romans presented a unified front. As Polybius wrote, "the maniples were nearer each other, or the intervals were decreased... and the maniples showed more depth than front".[13][49] Even though they outnumbered the Carthaginians, this depth-oriented deployment meant that the Roman lines had a front of roughly equal size to their numerically inferior opponents. The typical style of ancient warfare was to continuously pour infantry into the center and attempt to overpower the enemy. Hannibal understood that the Romans fought their battles like this, and he took his outnumbered army and strategically placed them around the enemy to win a tactical victory.[50]

Initial deployment and Roman attack (in red)

Hannibal had deployed his forces based on the particular fighting qualities of each unit, taking into consideration both their strengths and weaknesses.[51] This aspect of Hannibal's leadership was highlighted in the use of a Spanish unit, the Balearic slingers, whom he placed behind the infantry to hurl their ranged missiles into the masses of Roman troops.[39] He placed his Iberians, Celtiberians and Gauls in the middle, alternating the ethnic composition between Hispanics and Gauls across the front line, with himself at the front and center alongside his brother Mago.[52] Roman sources claim their placement was chosen for being the most expendable and unreliable troops, but modern reflections believe those forces were actually selected for their battle-hardening to carry the weight of the Punic side, as they would be tasked with the controlled retreat that ultimately made possible Hannibal's pincer movement.[53] Meanwhile, infantry from Punic Africa was on the wings at the very edge of his infantry line. This infantry would remain cohesive and attack the Roman flanks.[54]

Hasdrubal led the Hispanic and Gallic cavalry on the left (south near the river Aufidus) of the Carthaginian army.[55] By placing the flank of his army on the Aufidus, Hannibal prevented this flank from being overlapped by the more numerous Romans. Hasdrubal was given 6,000–7,000 cavalry, and Hanno had 3,000–4,000 Numidians on the right.[56][55]

Hannibal intended that his cavalry, comprising mainly medium Hispanic cavalry and Numidian light horse, and positioned on the flanks, would defeat the weaker Roman cavalry and swing around to attack the Roman infantry from the rear as it pressed upon Hannibal's weakened center.[57] His veteran African troops would then press in from the flanks at the crucial moment, and encircle the overextended Romans.[55]

The Romans were in front of the hill leading to Cannae and hemmed in on their right flank by the river Aufidus, so that their left flank was the only viable means of retreat.[58] In addition, the Carthaginian forces had maneuvered so that the Romans would face east. Not only would the morning sun shine low into the Romans' eyes, but the southeasterly winds would blow sand and dust into their faces as they approached the battlefield.[49] Hannibal's deployment of his army, based on his perception of the terrain and understanding of the capabilities of his troops, proved decisive.

As the armies advanced on one another, Hannibal gradually extended the center of his line, as Polybius described: "After thus drawing up his whole army in a straight line, he took the central companies of Hispanics and Celts and advanced with them, keeping the rest of them in contact with these companies, but gradually falling off, so as to produce a crescent-shaped formation, the line of the flanking companies growing thinner as it was prolonged, his object being to employ the Africans as a reserve force and to begin the action with the Hispanics and Celts." Polybius described the weak Carthaginian center as deployed in a crescent, curving out toward the Romans in the middle with the African troops on their flanks in echelon formation.[13] It is believed that the purpose of this formation was to break the forward momentum of the Roman infantry, and delay its advance before other developments allowed Hannibal to deploy his African infantry most effectively.[59] While the majority of historians feel that Hannibal's action was deliberate, some have called this account fanciful, and claim that the actions of the day represent either the natural curvature that occurs when a broad front of infantry marches forward, or the bending back of the Carthaginian center from the shock action of meeting the heavily massed Roman center.[60]

Destruction of the Roman army

The battle began with a fierce cavalry engagement on the flanks.[61] Polybius described many of the Hispanic and Celtic horsemen facing the Romans dismounting due to the lack of space to fight on horseback, and called the struggle "barbaric" in the sense of its utter brutality.[62] When the Carthaginian cavalry got the upper hand, they cut down their Roman opponents without giving quarter.[63][13] On the other flank the Numidians engaged in a way that merely kept the Roman allied cavalry occupied.[63] Hasdrubal kept his victorious Hispanic and Gallic cavalry under control and did not chase the retreating Roman right wing.[63] Instead, he led them to the other side of the field to attack the socii cavalry still fighting the Numidians.[64] Assailed from both sides, the allied cavalry broke before Hasdrubal could charge into contact and the Numidians pursued them off the field.[13][64]

While the Carthaginian cavalry were in the process of defeating the Roman horsemen, the masses of infantry on both sides advanced towards each other in the center of the field. The wind from the east blew dust in the Romans' faces and obscured their vision. While the wind was not a major factor, the dust that both armies created would have been potentially debilitating to sight.[49] Although it made seeing difficult, troops would still have been able to see others in the vicinity. The dust, however, was not the only psychological factor involved in battle. Because of the somewhat distant battle location, both sides were forced to fight on little sleep. Another Roman disadvantage was thirst caused by Hannibal's attack on the Roman encampment during the previous day. Furthermore, the massive number of troops would have led to an overwhelming amount of background noise. All of these psychological factors made battle especially difficult for the infantrymen.[65]

The light infantry on both sides engaged in indecisive skirmishing, inflicting few casualties and quickly withdrawing through the ranks of their heavy infantry.[66] As the Roman heavy infantry attacked, Hannibal stood with his men in the weak center and held them together in a controlled retreat. The crescent of Hispanic and Gallic troops buckled inwards as they gradually withdrew step by step. Knowing the superiority of the Roman infantry, Hannibal had instructed his infantry to withdraw deliberately, creating an even tighter semicircle around the attacking Roman forces. By doing so, he had turned the strength of the Roman infantry into a weakness. While the front ranks were gradually advancing, the bulk of the Roman troops began to lose their cohesion, as troops from the reserve lines advanced into the growing gaps.[67] Soon they were compacted together so closely that they had little space to wield their weapons. In pressing so far forward in their desire to destroy the retreating and seemingly collapsing line of Hispanic and Gallic troops, the Romans had ignored (possibly due to the dust) the African troops that stood uncommitted on the projecting ends of this now-reversed crescent.[60] This also gave the Carthaginian cavalry time to drive the Roman cavalry off on both flanks and attack the Roman center in the rear. The Roman infantry, now stripped of protection on both its flanks, formed a wedge that drove deeper and deeper into the Carthaginian semicircle, driving itself into an alley formed by the African infantry on the wings.[68] At this decisive point, Hannibal ordered his African infantry to turn inwards and advance against the Roman flanks, creating an encirclement in one of the earliest known examples of a pincer movement.[69]

When the Carthaginian cavalry attacked the Romans in the rear and the African flanking echelons assailed them on their right and left, the advance of the Roman infantry was brought to an abrupt halt.[70] The Romans were henceforth enclosed in a pocket with no means of escape.[71] The Carthaginians created a wall and began to systematically massacre them. Polybius wrote: "as their outer ranks were continually cut down, and the survivors forced to pull back and huddle together, they were finally all killed where they stood."[72]

As Livy described, "So many thousands of Romans were dying... Some, whom their wounds, pinched by the morning cold, had roused, as they were rising up, covered with blood, from the midst of the heaps of slain, were overpowered by the enemy. Some were found with their heads plunged into the earth, which they had excavated; having thus, as it appeared, made pits for themselves, and having suffocated themselves."[73] Victor Davis Hanson claims that nearly six hundred legionaries were slaughtered each minute until darkness brought an end to the bloodletting.[74] Only 14,000 Roman troops managed to escape (including Scipio Africanus, who managed to escape the encirclement with 500 men), most of whom had cut their way through to the nearby town of Canusium.

Polybius writes that of the Roman and allied infantry, 70,000 were killed, 10,000 captured, and "perhaps" 3,000 survived. He also reports that of the 6,000 Roman and allied cavalry, only 370 survived.[75]

Livy wrote, "Forty-five thousand and five hundred foot, two thousand seven hundred horse, there being an equal number of citizens and allies, are said to have been slain."[76] He also reports that 3,000 Roman and allied infantry and 1,500 Roman and allied cavalry were taken prisoner by the Carthaginians.[76] Another 2,000 Roman fugitives were rounded up at the unfortified village of Cannae by Carthaginian cavalry commanded by Carthalo, 7,000 fell prisoner in the smaller Roman camp and 5,800 in the larger.[76] Although Livy does not cite his source by name, it is likely to have been Quintus Fabius Pictor, a Roman historian who fought in and wrote on the Second Punic War. It is Pictor whom Livy names when reporting the casualties at the Battle of Trebia.[77] In addition to the consul Paullus, Livy goes on to record that among the dead were 2 quaestors, 29 of the 48 military tribunes (some of consular rank, including the consul of the previous year, Gnaeus Servilius Geminus, and the former Magister equitum, Marcus Minucius Rufus), and 80 "senators or men who had held offices which would have given them the right to be elected to the Senate".[76]

Later Roman and Greco-Roman historians largely follow Livy's figures. Appian gave 50,000 killed and "a great many" taken prisoner.[78] Plutarch agreed, "50,000 Romans fell in that battle... 4,000 were taken alive in the field and 10,000 in the camps of both consuls".[79] Quintilian: "60,000 men were slain by Hannibal at Cannae".[80] Eutropius: "20 officers of consular and praetorian rank, 30 senators, and 300 others of noble descent, were taken or slain, as well as 40,000-foot-soldiers, and 3,500 horse".[81]

Some modern historians, while rejecting Polybius's figure as flawed, are willing to accept Livy's figure.[82] Other historians have come up with far lower estimates. In 1891, Cantalupi proposed Roman losses of 10,500 to 16,000.[83] Samuels in 1990 also regarded Livy's figure as far too high, on the grounds that the cavalry would have been inadequate to prevent the Roman infantry escaping to the rear. He doubts that Hannibal even wanted a high death toll, as much of the army consisted of Italians whom Hannibal hoped to win as allies.[84]

Livy recorded Hannibal's losses at "about 8,000 of his bravest men."[85] Polybius reports 5,700 dead: 4,000 Gauls, 1,500 Hispanics and Africans, and 200 cavalry.[75]

Shield of Henry II of France depicting Hannibal's victory at Cannae, an allusion to France's conflict with the Holy Roman Empire during the 16th century.

Cannae played a major role in shaping the military structure and tactical organization of the Roman Republican army. At Cannae, the Roman infantry assumed a formation similar to the Greek phalanx. This left them vulnerable to Hannibal's tactic of double envelopment since their inability to maneuver independently from the mass of the army made it impossible for them to counter the strategic encirclement used by the Carthaginian cavalry. The laws of the Roman state requiring command to alternate between the two consuls restricted strategic consistency.

In the years following Cannae, striking reforms were introduced to address these deficiencies. First, the Romans "articulated the phalanx, then divided it into columns, and finally split it up into a great number of small tactical bodies that were capable, now of closing together in a compact impenetrable union, now of changing the pattern with consummate flexibility, of separating one from the other and turning in this or that direction."[98] For instance, at Ilipa and Zama, the principes were formed up well to the rear of the hastati—a deployment that allowed a greater degree of mobility and maneuverability. The culminating result of this change marked the transition from the traditional manipular system to the cohort under Gaius Marius, as the basic infantry unit of the Roman army.

In addition, a unified command came to be seen as a necessity. After various political experiments, Scipio Africanus was made general-in-chief of the Roman armies in Africa, and was assured this role for the duration of the war. This appointment may have violated the constitutional laws of the Roman Republic but, as Delbrück wrote, it "effected an internal transformation that increased her military potentiality enormously" while foreshadowing the decline of the Republic's political institutions. Furthermore, the battle exposed the limits of a citizen-militia army. Following Cannae, the Roman army gradually developed into a professional force: the nucleus of Scipio's army at Zama was composed of veterans who had been fighting the Carthaginians in Hispania for nearly sixteen years, and had been moulded into a superb fighting force.

Cannae is as famous for Hannibal's tactics as it is for the role it played in Roman history. Not only did Hannibal inflict a defeat on the Roman Republic in a manner unrepeated for over a century until the lesser-known Battle of Arausio, the battle has acquired a significant reputation in military history. As military historian Theodore Ayrault Dodge wrote:

Few battles of ancient times are more marked by ability... than the battle of Cannae. The position was such as to place every advantage on Hannibal's side. The manner in which the far from perfect Hispanic and Gallic foot was advanced in a wedge in echelon... was first held there and then withdrawn step by step, until it had the reached the converse position... is a simple masterpiece of battle tactics. The advance at the proper moment of the African infantry, and its wheel right and left upon the flanks of the disordered and crowded Roman legionaries, is far beyond praise. The whole battle, from the Carthaginian standpoint, is a consummate piece of art, having no superior, few equal, examples in the history of war.[99]

As Will Durant wrote, "It was a supreme example of generalship, never bettered in history... and it set the lines of military tactics for 2,000 years".[100]

Hannibal's double envelopment at Cannae is often viewed as one of the greatest battlefield maneuvers in history, and is cited as the first successful use of the pincer movement within the Western world to be recorded in detail.[101]

Apart from being one of the greatest defeats inflicted on Roman arms, Cannae represents the archetypal battle of annihilation, a strategy that has rarely succeeded since. As Dwight D. Eisenhower, the Supreme Commander of the Allied Expeditionary Force in World War II, wrote, "Every ground commander seeks the battle of annihilation; so far as conditions permit, he tries to duplicate in modern war the classic example of Cannae".[102] "Cannae" has become a byword for military success, and the battle is studied in military academies around the world. The notion that an entire army could be encircled and annihilated within a single stroke led to a fascination among Western generals for centuries (including Frederick the Great and Helmuth von Moltke), who attempted to create their own "Cannae".[74] Delbrück's seminal study of the battle influenced German military theorists, particularly the Chief of the German General Staff, Alfred von Schlieffen, whose "Schlieffen Plan" was inspired by Hannibal's double envelopment maneuver. Schlieffen believed that the "Cannae model" would continue to be applicable in maneuver warfare throughout the 20th century:

A battle of annihilation can be carried out today according to the same plan devised by Hannibal in long forgotten times. The enemy front is not the goal of the principal attack. The mass of the troops and the reserves should not be concentrated against the enemy front; the essential is that the flanks be crushed. The wings should not be sought at the advanced points of the front but rather along the entire depth and extension of the enemy formation. The annihilation is completed through an attack against the enemy's rear... To bring about a decisive and annihilating victory requires an attack against the front and against one or both flanks...[103]

Schlieffen later developed his own operational doctrine in a series of articles, many of which were translated and published in a work entitled Cannae.

In 1991, General Norman Schwarzkopf Jr., commander of coalition forces in the Gulf War, cited Hannibal's triumph at Cannae as inspiration for the rapid and successful coalition operations during the conflict.[104]