Outnumbered, Outgunned: How Underdogs Prevail

Dexterous, redoubtable, and adaptable, the army Hannibal led at Cannae -- just 55,000 strong or thereabouts -- relied on a supple interplay of cavalry and infantry that revealed years of instructive service. Numerous different warriors, from different lands and speaking different languages, took orders from the Barcid command structure that day and performed heroically. Only professionalism and long experience could account for this.

Like all ancient generals, Hannibal deployed his cavalry on the wings. (His elephants had all died by this point.) But unlike the Romans, he intended to use them for more than placeholders. On the right were the Numidians, bareback riders who wore virtually no armor and relied on volleys of well-aimed javelins to break up their enemies. The left wing was comprised of heavy cavalry -- Spanish and Gallic riders, the wealthier of them wearing mail shirts, who rode hard into battle in close order. Much more numerous than their Numidian comrades, these fearsome riders were entrusted to Hasdrubal, one of Hannibal’s most trusted lieutenants, who meant to shatter the Roman right wing.

But what about the center? Here Hannibal would have to receive the full force of around 80,000 legionaries. Some 24,000 close-order infantry spanned the middle of the Carthaginian line between the cavalry wings, the overwhelming majority of which were allied Celts recruited from the Po Valley. The rest, perhaps 8,000, were Spanish, armed with large oval shields and wielding an array of spears, javelins, and short thrusting swords on which the Romans would ultimately base their famous gladius. Among the Celts, only chieftains could afford a mail shirt and helmet, and they would have stood out amid their shirtless underlings -- fierce warriors armed with large shields, spears, and heavy slashing swords as much as three feet (0.9 m) in length. Out in front of the close-ranked Celts and Spaniards ranged skirmishers from all the nations in Hannibal’s army, though their numbers cannot be known.

With so few infantry to receive the expected Roman onslaught in the center, Hannibal made a decision that would echo down the ages as inspired. He ordered them to bulge forward in a crescent shape, with the very center forming a blunt point behind which the remaining units ranged outward en echelon. Behind the wings of this convex formation lurked two phalanxes of Libyan infantry. These were Hannibal’s finest, now sporting Roman arms and armor captured from enemy dead. Five thousand strong each, they anchored the whole line.

In the ritualized nature of ancient warfare, skirmishers, crowds of them preparing for battle in front of both armies, were the first to clash. They now tested each other on the plain, hurling missiles and occasionally closing to exchange blows. If either force were to have an impact on the coming battle, one of them would have to be pushed from the field. At Cannae, no such triumph seems to have occurred, resulting in a stalemate that gave way to the movement of regular troops.

Hasdrubal, preparing his heavy cavalry on the Punic left wing for an imminent charge, saw the Roman infantry start to advance and made his move. The Celts and Spaniards, many of them nobles in their tribal cultures and resplendent in mail and plumed helmets, thundered across the field, directing their accelerating mounts into the Roman right wing. There, cavalry under Paullus himself awaited their arrival with what must have been mounting dread. In addition to being outnumbered on this part of the line, the Romans had yet to best Punic cavalry in a fight, and must have anticipated a vicious struggle.

It came soon enough. Once in among each other, the two sides clashed in a maelstrom, the sources implying that many were pulled from their mounts and continued fighting on foot. The Romans were outmatched, and soon fled for their lives, those on foot either falling to Punic spears or -- as Paullus himself did -- making their way to the infantry to continue fighting there.

On the Carthaginian right, the Numidians wrangled with the Roman left wing, whose horsemen fought under Rome’s supreme commander that day, Gaius Terentius Varro. Less numerous than their Gallic and Spanish colleagues on the opposite end of the line and also incapable of closing decisively, they wheeled and turned, hurling volleys of javelins against Varro’s cavalry. An impasse had been reached, with neither side willing or able to sweep the other from the field.

Trapped

The center, by contrast, surged with savage collisions. Here the Roman legions had at last reached their destination, striding into the violence with the confidence of numbers. At the apex of the Punic crescent, Gauls and Spaniards fought desperately against the enemy, only to fall back before the punishing pressure of the hastati and principes. Before long, their cause seemed hopeless, and the bulge began to collapse. The tremendous Roman numbers, it seemed, were telling.

The plight of the Carthaginian center belied Hannibal’s understanding of the situation. By forcing his line outward to begin with, he had ensured that the Roman infantry would be pulled almost inexorably into the Punic center as it fell back like a collapsing bubble. Hannibal had intended to use the Romans’ own momentum against them, and it was working.

But it was the cavalry that made the next decisive move. Having regrouped and rested his heavy cavalry after driving Paullus’s wing from the field, Hasdrubal launched his horsemen clear across the rear of the Roman center to clash headlong into Varro’s cavalry, still sparring with the Numidians. Varro, engaged on two sides and now wildly outnumbered, broke and wheeled in abject flight.

He never saw the climactic developments in the center that he had helped set in motion. As Hannibal’s Gauls and Spaniards gradually gave ground and then broke altogether before the Roman juggernaut bearing down on them, the inversion of Hannibal’s line pulled the Romans in as if by suction. By the time the legions were smelling blood and reveling in the chase, they were already well inside a trap that had been carefully laid for them.

Soon the Libyans, as yet unengaged and fresh, closed like a vise on the flanks of the oncoming legions. Roman cohesion had in all likelihood become a sham by now, as hastati, principes, and triarii all pushed forward with a mass of warrior energy. Resistance against the oncoming Libyans, deliberate and grim faced behind their captured helmets, was no doubt fierce at first but confused. Many in the Roman ranks now clearly understood the scale of their predicament, sending a wave of subdued panic through the masses. They had been corralled like cattle.

Those at the front of the corral had no idea what was breaking on the rear. Hasdrubal, having vanquished both Roman wings with his corps of hard-driving cavalry, now proceeded to savage the Roman rear as it advanced clumsily forward. The trap was closed.

Once Hannibal’s retreating center rallied and turned on its embattled pursuers, the Roman army -- still close to 80,000 strong -- found itself hemmed in from nearly every direction. Hannibal may well have hoped for this outcome, but the completeness of his triumph was probably beyond even his wildest dreams.

He still had a huge enemy to subdue. And Romans were not in the habit of laying down their weapons in times of mortal crisis -- quite to the contrary, in fact. This partially explains what followed: a drawn-out, exhausting horror show of slaughter between two foes who had long since embraced the idea of war without quarter. Despite Hannibal’s penchant for taking allied prisoners and treating them well in the interest of breaking their ties with Rome, the fury of Cannae had gone too far to permit restraint. The Libyans in their thrusting phalanxes, the Gallic and Spanish infantry with their tribal war bands, and Hasdrubal’s pounding horsemen, all killed their way into the center against legionaries fighting desperately in a thousand separate melees whose participants were incapable of comprehending the totality of the calamity closing in on them.

Given the size of the disaster, the bloodletting must have proceeded throughout most of the day. Rome’s loss screams out to us still: 50,000 dead, a figure so conspicuous that historians have mulled over it ever since. Polybius, whose writings remain a primary window into the military affairs of the Republic, gave a figure of 70,000 dead. Livy, a Roman historian writing during the first century BCE, offers a figure of 50,000, which has acquired the weight of orthodoxy over the years, not least because it is simply more comprehensible. Nobody in the records gives a smaller figure.

This is simply staggering. Cannae’s death toll (Punic losses were between 6,000 and 8,000) sounds more like plague mortality. No army in antiquity had likely suffered anything like this, amounting to a near-gutting of Rome’s militaryage manhood. Descriptions of the battlefield are graphic even for ancient sources, conjuring images of a plain packed with eviscerated dead and dying, the survivors lingering in a kind of hell.

“Some they found lying with their thighs and knees gashed but still alive,” writes Livy, “these bared their throats and necks and bade them drain what blood they still had left. Some they discovered with their heads buried in the earth, they had evidently suffocated themselves by making holes in the ground and heaping the soil over their faces.”

As far as anyone knows, no general had ever performed a maneuver of such perfection before Hannibal’s uncanny achievement. It remains the exemplar of double envelopment today, studied by aspiring military geniuses around the world. Norman Schwarzkopf claimed to have relied on the lesson of Cannae in his execution of Desert Storm.

In the event, it did Hannibal little good. This is perhaps the greatest indictment of his efforts. Though unmatched in tactical expertise, the famous son of Hamilcar had only a myopic vision of how victories on the battlefield could decide events. More to the point, he misunderstood the nature of his enemy.

Rome fought on -- an achievement as astounding as Hannibal’s at Cannae. Some of Rome’s southern Italian allies defected to the Punic cause, but Rome held on to most of the loyalties that allowed her to field such enormous armies. In the end, Hannibal would become little more than a glorified brigand in the Italian countryside. Rome, utterly unyielding, drew Hannibal out of Italy by threatening his North African homeland. The war ended in 201 BCE with a string of Roman victories.

Cannae remains a perfect example of the worth of superior generalship over superior strength. Assured of his abilities before the fight even began, Hannibal delivered a coup de grace that had been planned as soon as the opposing armies formed up for combat. For this, as much as his legendary crossing of the Alps, Hannibal remains a fixture in the popular imagination.

Excerpted from Outnumbered: Incredible Stories of History's Most Surprising Battlefield Upsets by Cormac O'Brien. Copyright 2010 by Cormac O'Brien. Reprinted by permission of Fair Winds Press.