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. 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. 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.
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. 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. 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. 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.
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, 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. 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.
The Roman battle plan at Cannae can be summarized in three words: “pack the middle.” Because this approach would play into Hannibal’s own scheme and lead to a great disaster, it is easy to dismiss the plan as nonsensical. It wasn’t. Rather, it had a clear purpose, to maximize the Roman numerical advantage in infantry while minimizing the obvious Carthaginian superiority in cavalry. It was also based on past experience. At Trebia, ten thousand legionaries had finally managed to hack their way through the center of the Punic line, and had they been able to do it sooner, they could have split and pivoted to crush the Carthaginians attacking on each flank. Even amidst the surprise and demoralization of Trasimene the impetus of around six thousand Romans had carried them through the Carthaginian stopper force, only to be captured later. We can assume that Varro and Paullus and those advising them were confident in the ability of their troops to puncture the heart of the Punic line, and were intent on doing this as rapidly as possible. Geometrically this called for a narrow, thick formation, exactly the configuration on the day of the battle described by Polybius (3.113.3), “placing the maniples closer together than was formerly the usage and making the depth of each many times exceed its front.”
Breaking though in this manner was decidedly not a matter of simple momentum, like some gigantic rugby scrum pushing inexorably forward. Romans fought primarily with short swords, so the cutting edge was by definition the first line of combatants. True, pila could be launched from several rows back, but any soldier behind around line eight would probably have hit a fellow Roman up front.
The real arguments for this type of human geometry had to do with order, endurance, and psychology. Long narrow columns are easier to keep together, and, they therefore move faster and more cohesively on the battlefield. The many lines to the rear also insured an almost inexhaustible supply of fresh fighters to take the place of the fallen and exhausted, a kind of conveyor belt of shark’s teeth. Finally, a great many of the Roman participants at Cannae lacked combat experience; the middle of such a formation was a safe, psychologically reassuring place for them. One source equates this to the human instinct to herd together for mutual comfort, but without considering that this was actually prey behavior. The thickened manipular order could be expected to have massive combat endurance, which would make the formation almost impossible to defeat by frontal attack, and would thereby allow the unit to move steadily forward. But what would happen if it faced the unexpected, was hit from an unanticipated direction? At this point herding behavior might become just that, dissolving the maniples into a crowd compressed to the point of mass helplessness. The legions would lose the ability to replace frontline fighters through now nonexistent gaps between units. It was a prospect not pleasant to contemplate, and one we can be pretty sure the Romans failed to consider.
Hannibal may have. Just how much he knew of the Romans’ plans prior to battle is impossible to say. Though Livy (22.41.5–6) maintains that “all the circumstances of his enemies were as familiar to him as his own,” whether Hannibal understood beforehand the degree to which the Romans would pack the middle remains open to question. Yet his experience fighting them would have warned him of their will and of their ability to break through in the center, and the likelihood of their trying it again. Also, given his knowledge of Greek military practice, he was doubtless familiar with the Athenian tactics at Marathon in 490, when the Greeks withheld their center and crushed the Persians with their wings. As the day of battle approached, all of this must have been taking root in Hannibal’s fertile brain as he roughed out the framework of an even more lethal trap. As we shall see, the final details would await the contingencies of the battlefield, but the basic plan of using the Romans’ own greatest strength against them was inherent in Hannibal’s deployments and therefore had to have been plotted in advance.
Though there is a tradition of viewing Hannibal as simply being up to his usual tricks—hidden attackers and fake surrenders—the key deception at Cannae was far more subtle. In essence, the trap was hidden in plain sight, something that even today does not seem to be fully understood. Basically he planned to string a line of combined Gauls and Spaniards between two very deep columns of Libyans positioned on either flank, so that viewed from above the formation would look like a backward block letter C. The idea was that as the legionaries rushed forward, the Gauls and Spaniards would give way in a measured fashion (this was critical), leading the Romans farther and farther in between the two columns of Libyans, who would then be in a position to stage a devastating simultaneous attack inward from either flank, stopping the Romans dead in their tracks and leaving them all but surrounded.
Maps of the battle, which are invariably drawn from a bird’s-eye perspective, make the net results clear enough, but also reveal the central deception in a way that leaves open the question: “Why would anyone be dumb enough to walk into such an obvious trap?” But from ground level it would have been far from obvious.
The analogy of American football is helpful. This very intricate game can be enjoyed and understood by the public precisely because it is viewed from on high; the deception is designed to be seen at ground level, and from this perspective deceptions are profoundly confusing, requiring all manner of coaching, cues, and experience so that players are not fooled on every play. As the Romans approached the Carthaginian line, all they would have seen was a continuous line of men, with no way of knowing the varying depth at either side. As the Romans pushed forward, their attention would have been focused straight ahead and toward the center, where they were making the greatest progress. When the Punic flanks attacked, most of the Romans would not have realized it was even happening. They would have known only that their body of men had strangely come to a halt. By this time it would have been too late. They were as good as dead.
Assuming that Hannibal did not have direct knowledge of the Romans’ plans and simply had to anticipate what they might do, the Carthaginian’s plan faced several worrisome contingencies. Expecting his adversaries to pack the middle implied they would deploy on a fairly narrow front, not much wider than his own. Should the Romans march onto the battlefield in a more normal formation, their advantage in numbers would leave the Carthaginian line seriously outflanked on both sides, affording a perspective that would not only betray the depth of the Libyan columns, but also would force the Carthaginians to abandon the ambuscade by pivoting outward to make up the difference. Also, the Roman and allied cavalry could not be ceded the initiative; if they were allowed to sweep around to either side of the Carthaginians, the jaws of the trap would be revealed and their commanders could be warned before it was too late. None of this happened; instead the Romans played into Hannibal’s hands as if choreographed; but such schemes are always vulnerable to the unexpected and this could account for the shadow of what is possible to interpret as Plan B in the sources—Appian’s (Han. 20) story of Hannibal concealing some cavalry and light troops in ravines on a hill (presumably the bluffs leading up to Cannae) with orders to attack the enemy rear as at Trebia, and Livy’s (22.48) tale of 500 Numidians staging a fake capitulation, being conducted behind enemy lines, and later producing hidden swords and assaulting from this quarter. Neither is taken very seriously by modern historians; but they were hardly out of character for a fox full of tricks.