The Ghosts of Cannae: Hannibal and the Darkest Hour of the Roman Republic

by Robert L. O'Connell

  It is not clear when the two forces joined together. Polybius (3.106.3) talks about sending new recruits forward for experience skirmishing, but these recruits appear to be reinforcements for the legions already at Gerunium. Although Livy (22.40.5) maintains that the new legions arrived before Hannibal left winter camp and headed toward Cannae, modern opinion14 favors a delayed linkup, as late as less than a week before the battle. Given this, it’s hard to imagine that the Romans’ juggernaut was in any meaningful way integrated; rather, it remained two separate armies that on the day of battle would be cut up and welded together for its moment of truth, tactically a dubious proposition.

  Yet it could be argued, and probably was at the time, that the Roman military system made their troop formations inherently interchangeable, and therefore more easily mixed and matched. No doubt the injection of experienced leadership was counted upon as a lubricant. And there was the intangible of morale. The allied forces in particular were furious over Hannibal’s rampage across the Italian countryside and were vengefully eager for combat. Meanwhile, the Roman troops seem to have been embarrassed, not daunted, by previous defeats and were now grimly determined to prevail.15

  To seal the deal, the establishment did something unprecedented. Livy (2.38.2–5) tells us that once the allied levies arrived, the consuls had the military tribunes formally administer an oath to all the infantry and cavalry that they would depart from their ranks only to secure a weapon, kill an adversary, or save a comrade. Previously, the historian notes, this had been a voluntary pledge among the soldiers themselves; now flight in the face of the enemy was against the law. To some societies and some armies this might have seemed a mere formality, but the Romans were literalists and legalists. And as we shall see, it was this oath that would determine the fate and futures of those who might have thought themselves otherwise lucky to escape the death trap at Cannae.

  As a fighting force, the fated quadruple consular army was large and full of Romans, both good things. But it was also full of vulnerabilities. It had a substantial number of light troops, perhaps as many as twenty thousand, but they were of suspect quality. If not the “armed servants” one source calls them,16 they were clearly not as effective as their Carthaginian equivalents. These soldiers had been scattered like chaff at Ticinus and Trebia … though they did seem to stiffen somewhat under Fabius and Minucius. Still, it is probably telling that Rome’s staunch ally, old King Hiero of Syracuse, looking for ways to help, thought it wise to donate one thousand light troops of his own, some of them archers (apparently the only archers at Cannae).17

  The cavalry was probably even weaker; it had already suffered savage losses, and the skills involved are not easily replicated on short notice. The ranks were probably swelled a bit by members of the senate, who were by definition equestrians, yet many would have been old and past their military prime. Besides, the majority of cavalry were allies, and Hannibal’s well-advertised leniency toward them could be expected to have an impact on their fighting spirit in a pinch, especially among forces with the greatest ability to get off the battlefield in an emergency.

  The obvious strength of the Cannae army was its heavy infantry. Even if it could not be screened effectively by light troops and its flanks protected by cavalry, it was big enough to be relatively immune from harassment, provided it could maneuver and win decisively with some degree of dispatch. Yet this was also a force subject to emotional volatility—its better half, the experienced element, had been defeated more than once by Hannibal, and the other part was a mass of neophytes, with all that that implied. Temperamentally, it was an army likely to overreact—prone both to excessive enthusiasm and passive despair. Judging by his plan and its results, this was exactly what its Barcid nemesis anticipated.

  [3]

  It is not certain when Hannibal left Gerunium and headed south, but he likely would have waited until the early summer, when the crops were ripening and his troops could forage. Livy concocts a tale of an attempted ambush and then a night escape in the face of the already united Roman army, but Polybius’s version that Hannibal marched out past the guarding force of Geminus and Regulus, who were under orders not to engage until Varro and Paullus arrived with the rest of the army, is simpler and more plausible.18 The historians agree on one point: the Punic force was hungry. Whether on the basis of good luck or good intelligence, Hannibal gravitated to Cannae, around sixty miles south of Gerunium, nearly to the Adriatic coast. Here he captured a grain storage and supply dump in the ruined citadel on the heights of the otherwise abandoned town. His food problem solved, at least temporarily, he made no further effort to move, and this was telling.

  Cannae sat at the bottom edge of an immense treeless plain, the largest south of the Po.19 It was ideal for cavalry operations and large-scale maneuvers, exactly the terrain for magnifying Punic military advantages. By this time Hannibal probably understood that the Romans were intent on a showdown and were putting together a monster of an army for the occasion. So far, his efforts to chip away at the Italian alliance had come to nothing. He needed a really spectacular victory to generate the kind of political impact to begin breaking off Rome’s affiliates. This was the perfect time and place to inflict it. Staying here was tantamount to accepting the challenge. He had only to await his opponent’s arrival.

  But, being Hannibal, he probably kept himself busy preparing the reception. If we accept Polybius’s version of the events leading up to the battle, the Punic army may have been alone at Cannae for several weeks.20 This is a dangerously long time to give any commander to prepare a battlefield, much less a commander with Hannibal’s fertile military imagination. By this time he was likely on a first name basis with every rise and depression, every twist in the River Aufidus, every potential campsite, every approach and escape route, every possible advantage he could squeeze out of the surroundings and then blend with a battle plan that seems to have been derived from his cumulative observations of Roman fighting tendencies and the capabilities of his own troops. As always, much remained to be determined by chance and the circumstances of the actual engagement, but it’s a safe bet that during this respite Hannibal’s mind seldom wandered from the upcoming test.

  His plan when it was finally hatched implied a great deal of faith in his army. This faith was not misplaced. The gang of desperadoes that had stumbled off the Alps not much more than a year and a half earlier had been but a scrawny prototype of the force that now awaited the Romans at Cannae. Freeze-dried no more, the men and horses had regained their health, had eaten their fill, and were rested. We know that key elements had been systematically rearmed with the best of the captured equipment, and it is likely that many others had picked up bits and pieces of what had once been Roman weaponry.

  Another change had to do with the Gauls. By this time they were much more reliably integrated into the fighting force. They still fought together, to take advantage of their peculiar tactical characteristics, but at Cannae small units of Gauls were interspersed with Spaniards, indicating that their tribal allegiances had been effectively superseded by the command system that controlled the rest of the army.21 Very likely the process that had begun for the Gauls on the slog through the Arno marshes was now complete. They were now not only fierce and brave individually; they were also disciplined, well trained, and above all reliable at the unit level. And as such they would play a critical role at Cannae.

  Psychologically, this was an army that had known nothing but the most decisive sort of success since it had entered Italy. In a life-and-death struggle, confidence is crucial, and the recent past had given these men every reason to believe in their own fighting skills, as well as their commander’s ability to drive opponents into positions of utter vulnerability and near helplessness. Many must have already killed Roman soldiers personally and must have also observed them reduced to an abject state, begging for mercy. That was Hannibal’s point when he reassured an officer worried about the size of the opposing force at Cannae. (“In all thi
s multitude there is no one who is called Gisgo.”) For Carthaginians, more Romans simply meant more Romans to kill. This was the dark side of a truly professional fighting force, especially one that fought with edged weapons; they were used to killing, inured to it. They would kill without hesitation. It was a terrible advantage that the Carthaginians had and that most of the Romans at Cannae lacked.

  Nowhere was this more evident than in the cavalry, probably the most lethal Punic fighting component. As had been true since Trebia, the Spaniards and Gauls rode together as a shock element, although now they were almost certainly better trained and integrated. The Spaniards carried two light throwing spears, a sword, and a round shield, or caetra. The Gauls, primarily composed of nobles, were more heavily armed and armored, with chain mail, metal helmets, and a stout thrusting spear. The two groups would have been an impressive one-two combination, with an initial hail of javelins followed by closer, more decisive engagement.22 This was a force more than capable of taking on anything the Romans had on horseback, and likely predisposed to fight in the same very confrontational way—one entirely different in its ethos from the other face of Punic cavalry.

  They were the Numidians, Hannibal’s version of killer bees, proverbially swarming their opponent if given even the slightest opening. The Numidians were the closest thing a western Mediterranean battlefield saw to an inner Asian steppe horseman. They lacked only the steppe horseman’s deadly composite bow, relying instead on a brace of light javelins and a slashing dirk. Characteristically, Numidians pinned and herded their foes through absolute mastery of their hyper-agile ponies, and then ran the enemy down with ruthless efficiency, able to cut their hamstrings even at a full gallop. Like the steppe horsemen, they were fatally easy to underestimate. Riding bareback and carrying only a light shield for protection, they avoided hand-to-hand combat and were largely incapable of direct confrontation. Polybius (3.72) describes them as “easily scattered and retreated, but afterwards wheeled round and attacked with great daring—these being their peculiar tactics.” Yet in the hands of a commander as opportunistic as Maharbal, they could destroy an entire force once it became even slightly demoralized and ready to bolt.

  All together, Hannibal’s cavalry now numbered around ten thousand, two thirds more than when he’d entered Italy, and more to the point, they were enjoying a five-to-three quantitative edge over the Cannae-bound Romans, whose horsemen were by far inferior in quality also. Looked at another way, the Carthaginian force had one horseman for every four foot soldiers, while the Roman ratio was one to thirteen, a strong indication that the Punic army was far better adapted to the flat terrain on which the battle almost certainly would be fought. All in all, it constituted a yawning gap, and one that would soon send the Romans stumbling down the initial steps toward tactical ruin.

  Numerically, the Carthaginian advantage in cavalry was nearly reversed with regard to infantry. Polybius and Livy both agree that forty thousand foot soldiers would have been available to Hannibal at Cannae, a figure modern sources support.23 But if the infantry were outnumbered two to one, the quality of the Punic soldiers was better, and not just in terms of confidence and prior experience killing Romans. The Carthaginian force was notably less homogenized than its Roman equivalent, and in those various parts were vested a variety of fighting skills tailor-made for a commander with Hannibal’s protean military imagination. The ancient sources provide no specific figures for the various contingents, but modern historians have made a number of informed estimates that seem basically in agreement.24

  The approximately eight thousand Punic light troops were probably proportionately even more outnumbered by the Roman velites than was the case with their comrades in the other infantry arms, but the relative difference in personal capabilities was equivalently lopsided in the other direction. Basically, Roman skirmishers were men either too young or too poor to take their place in the maniples. The Carthaginians were specialists—screening and harassment was their business.25 Numidian javelin men, perhaps six thousand of the total light troops, proved particularly adept at cooperating with their horse-borne countrymen and seem to have intensified the effects of the cavalry’s swarming tactics. Though less numerous, the other major component of the Carthaginian light infantry—the Balearic slingers—were, if anything, individually even more lethal. They were both feared and coveted as mercenaries throughout the western Mediterranean. Much overlooked by modern historians, the sling was capable of launching a projectile toward its target at up to 120 miles per hour—fast enough to kill a man at fifty paces.26 While light troops in general played a secondary role at Cannae, at least until the later stages, one shot delivered by a slinger early in the battle may have played a critical role in compromising the Roman leadership.

  Hannibal’s close order heavy infantry probably numbered around thirty-two thousand at this point and came in three varieties: Gauls, Iberians, and Libyans. Despite the heavy infantry’s having suffered relatively severe casualties at Trebia and Trasimene, there probably remained around sixteen thousand Gauls, whose shock value and increased reliability we have already considered. There were likely about six thousand Spaniards left at this point, a fraction of the original contingent that had made up the bulk of the army when it had departed New Carthage. In Darwinian terms, we can assume the fittest survived. Nevertheless, Polybius (3.114.4) leads us to believe they wore no armor, but only a purple-bordered linen tunic, and possibly not even a helmet; but since a lot of captured Roman equipment was available, this may not be entirely accurate. Tactically, these Iberians were most interesting because they fought like Romans, first throwing a heavy javelin not fundamentally different from a pilum, and then weighing in with either a straight or a curved short sword and a large oval shield. Interspersed with Gallic units, they could be construed as having had a stabilizing effect on the critical center at Cannae, allowing the more impulsive Gauls to rush forward, hack away for a while, and then fall back, leaving the Spaniards to fight the pursuing Romans on their own terms.

  Finally, there were the Libyans, presumed to be Hannibal’s best-drilled and most elite maneuver element, since they were the first to receive Roman equipment and because they formed the jaws of the trap that snapped shut on the Romans at Cannae.27 Thus far he had used them scrupulously and in ways they would take few casualties, so of the twelve thousand who had come down off the Alps, probably around ten thousand remained. But if these African spear-fighters formed the teeth of the Punic force structure, the other elements were the claws and muscle and sinew of this beast of battle. Hannibal’s genius as a commander was his ability to devise and execute a plan that used all the parts in concert to swallow and digest a much larger prey.

  [4]

  We pick up the Roman juggernaut where we left it at the beginning of Chapter II, slouching toward Cannae, proceeding with the utmost caution. The Romans may have found the flat coastal terrain reassuring, since it gave Hannibal nothing to hide behind should he try to stage an ambush. No doubt they sent the cavalry out to reconnoiter just in case.

  According to Polybius’s version, the two halves of the great army probably joined up on the road in late July, with Geminus (Regulus, the other proconsul, seems to have been sent back to Rome because of advanced age, to be replaced by Minucius) having followed Hannibal south at a respectful distance, and Varro and Paullus intercepting Geminus near Arpi, roughly two days’ march north of Cannae. With the army combined, there were eighty-six thousand mouths to feed. So it made sense to keep the contingents separate for as long as possible. The hunger of the army would also place time constraints on the commanders to seek decisive combat once they got within striking distance of Hannibal. Ironically, it seems perhaps the dinner tables had turned; though Livy (22.40.7–8) would have us believe that as battle approached, Hannibal was also running out of food. If true, and not merely the historian’s way of saying Fabius had been right all along,28 both sides needed a fight quickly.

  The Romans had no trouble locating
Hannibal, since he was hardly hiding, and they set up camp initially approximately six miles to the east on the broad plain that runs down to the Adriatic. There ensued an elephantine pas de deux, as the two armies warily closed the distance while at the same time trying to gain some tactical and psychological advantage.

  The Romans, however, were literally of two minds, since Varro and Paullus followed the tradition of alternating command daily when consuls operated together—just what Fabius had refused to do the year before, which had thus enabled him to save Minucius. Because of the curtain of blame later cast over Varro, it is hard to separate actual disagreement between the two consuls from aspersions dumped on Varro retrospectively. If it is conceded that both consuls wanted to fight, and most modern historians do concede this, the evidence such as it is points to Paullus as the more cautious of the two, particularly worried about being caught on the flat ground ideal for Carthaginian cavalry.

  The vicinity of the anticipated field of battle was dominated by high ground to the southeast, where the abandoned town of Cannae and Hannibal’s first camp were located, and bisected by the River Aufidus, a shallow, narrow watercourse running in a northeasterly direction toward the sea. The terrain to the northwest, over and beyond the left bank of the river, was broad and flat. The area between the right bank and the highlands toward Cannae, while still level, was more broken and constricted. Hannibal almost certainly preferred the left bank but could and would fight on the right side; both Roman consuls wanted to avoid the left side and stage the battle in the most confined area possible. The days preceding August 2, 216, were an extended test of wills that saw Hannibal unsuccessfully harass the Romans with light troops as Varro initially approached. Then Hannibal moved his camp to the left bank and formally offered battle on this side, first to Varro and then to Paullus, only to be refused. Finally, Hannibal sent Numidians after the Romans’ water bearers, and this gesture provoked the Romans into action, albeit on the right side of the Aufidus.29 Meanwhile, the Romans had moved too close to withdraw safely, and so they split their army into two camps, leaving two thirds on the left side of the river and the remainder in a smaller enclave on the right bank. The stage was set.