The defeat of August 216 B.C. is usually attributed to three factors: the Romans were poorly commanded and deployed; they faced a military genius in Hannibal; and they were demoralized from a string of three defeats in the past twenty-four months that had cost them thousands of their fathers, sons, and brothers. All three explanations have merit. The Roman plan of battle at Cannae was poorly thought out. It made no sense for legions to mass on narrow, flat terrain where they might be trapped and squeezed between flanking enemy infantry pincers and rapidly moving mounted troops at their rear. In these natural or man-made valleys and canyons, infantry companies had no chance to flow independently but were prone to conglomerate and could thus be hacked at from all sides. With no room to maneuver to the side, individual legionaries lost open space and the crucial ability to use their swords with advantage. Like underpowered phalangites—who had wielded massive pikes, not short swords—they were to be funneled against columns of Hannibal’s heavily armed swordsmen and spearmen. Legionaries in dozens of columns to the rear were waiting in line, as it were, helpless to prevent their own predictable annihilation to come. The Roman army would go on in the next century to smash through columns at the battles at Cynoscephalae, Magnesia, and Pydna by outflanking and outmaneuvering far more clumsy Greek phalanxes. They would learn that the way to beat foreign armies of the Mediterranean was to fight in a manner opposite from their charge at Cannae.
Due to Hannibal’s string of unbroken successes during his descent through northern Italy (218–216 B.C.), the Senate had transferred command of the legions from its brilliant general Fabius Maximus—given pro tempore dictatorial powers in the field—back into the hands of its annually elected consuls, who for the year 216 B.C. were the aristocratic and careful L. Aemilius Paulus and the more adventuresome Terentius Varro, the latter purportedly a popular leader of the masses. Scholars have criticized Varro’s decision to march the army on the morning of August 2 across the Aufidus River into the flat, treeless plain of Cannae (command rotated between the consuls on alternating days). In fact, the Roman general had reason to initiate battle, since Hannibal’s mounted patrols were raiding his lines, devastating the surrounding countryside, and making it ever more difficult to keep such a huge force well supplied. The specter of such a huge army gave his men confidence that at last they could catch Hannibal in an open plain. Their superior numbers and organization might annihilate his mercenaries, who would have no chance for ambush or cover by darkness or fog. A year earlier Roman weight had almost crushed the Carthaginians at Lake Trasimene before being entrapped and outflanked in the mist. At Cannae the plain was relatively flat, the weather windy but reasonably good, and the Carthaginians seemingly deployed only in front of the legions, making the resort to deception unlikely.
Varro’s real mistake lay in committing most of his forces at once— only 10,000 Roman reserves were left behind far from the battlefield in two camps on either side of the river—without keeping a third line ready to exploit success or prevent collapse. In any case, because Varro either worried about the quality of his new replacement recruits or desired to ensure that his army was not strung out too far, he reduced his battle line to about a mile. Out of an army of between 70,000 and 80,000, not more than 2,000 could engage the enemy at the front in the initial attack. The depth of the Roman mass in some places along the long line was well beyond thirty-five men, and as great as fifty—the deepest formation in the history of classical warfare since the great mass of the Theban army had obliterated the Spartans at Leuctra (371 B.C.). But at that earlier battle, the Theban column met few cavalry and a timid king, and was led by the gifted tactician Epaminondas.
There may have been only 40,000 Carthaginian infantrymen facing an army almost twice that size. Surely, most other enemies who faced such a huge force would have crumbled before the legionary onslaught. The difference was in large part due to the tactical genius of Hannibal, who adapted his battle plans precisely to facilitate the impatience of Roman tactics. As we have seen, Hannibal and his brother Mago stationed themselves with the less dependable Gauls and Spaniards right at the acme of the Roman attack, convinced that their presence could steady their unreliable troops long enough to conduct a gradual withdrawal, to backpedal slowly, sucking in the oncoming Roman weight. The Punic center was bowed out toward the Romans—Polybius called the curious formation a mēnoeides kurtōma, “a crescent-moon-shaped convexity”—both to hide somewhat the African pikemen on the wings and to give the impression that the line was deeper than it actually was. The bulge allowed a margin of retreat: the greater the distance the center backpedaled without collapse, the easier the wings might envelop the narrower Roman formations.
The key for Hannibal and his European allies was to survive until North African infantry on the wings—the elite of Hannibal’s army—and cavalry streaking to the rear and sides could enclose the enormous legionary mass, thereby deflating its forward pressure before it smashed the core of the Punic army. Livy noted in his history of Rome that the Punic center was far too thinly deployed “to withstand the pressure” (22.47). The problem was that there were not more than 2,000 to 3,000 legionaries at the front of the huge column who were actually fighting with drawn weapons; the others, more than 70,000, were pushing blindly ahead on the assumption that the cutting edge of their army was mowing down the enemy in front. The least trained were probably on the wings—and thus the first to confront the closing jaws of Hannibal’s superb African infantry. Whatever the estimation of our ancient sources concerning the Gauls and Spaniards, they fought bravely and in some sense saved the battle for the Carthaginians.
Just in time, the charges of African horsemen at the flanks and at the back, the ubiquitous barrage of missiles, and the sheer confusion of seeing enemies in all directions stalled the Roman advance. Hannibal, in broad daylight and without cover, had created an ambush by the sheer deployment and maneuver of his men—and he had done so while battling at the apex of the Roman assault, convinced that his physical presence in the maelstrom would allow his outnumbered and exhausted hired Iberians and Gauls to backpedal without collapsing. The envelopment was soon completed. A thin wall of Punic and European irregulars held tight a surging throng of Roman infantry. Had each legionary killed one man before dying, the battle would have been a decisive Roman victory. Had they known that their adversaries were only two or three ranks deep, the legions might have broken out. The wind, dust, noise, and panic brought on by rumors that the enemy was everywhere only added to the chaos. Because of the enormous losses during the prior two years at Trebia and Trasimene, the Romans at Cannae were fresh recruits without many veterans to calm their fears, and thus immediately became demoralized at the realization that for a third time an enormous Roman army was being led into a Punic trap from which few might escape alive. Many must have been adolescents and so have frantically thrown down their weapons the second they realized they were trapped. The great strategist Ardent du Picq believed that Hannibal had guessed right that the “terror” and “surprise” resulting from his encirclement would outweigh “the courage of despair in the masses.” In short, panic killed the legionaries at Cannae. Still, for a time the prominence of so many Roman luminaries on the field of battle—like the presence of doctors, lawyers, and other elites at the gates of Auschwitz—must have given some the false reassurance that total destruction was impossible. The army at Cannae was larger than the citizen population of every city in Italy except Rome, and contained enough aristocrats to have run most of the legislative and executive branches of the Italian republic.
Hannibal Barca (“Grace of Ba‘al Lightning”) had little respect for legionary repute. At nine he had sworn an oath of eternal hatred toward Rome—dramatically portrayed in Jacob Amigoni’s magnificent oil canvas—and was one of the few foreigners in the entire history of the ancient world who actually welcomed frontal assault against Western armies. The African desired to break Roman legions outright in the field, as part of his larger plan to discredit the entire notion of Roman military invincibility, and so systematically uncouple Rome’s allies in central and southern Italy.
Shattered and disgraced legions meant a weak and divided Italy, which would leave Carthage free to arrange its mercantile affairs in the western Mediterranean as it saw fit, and at the same time avenge the shame of defeat of the First Punic War (264–241 B.C.). From the time of his descent from the Alps in October 218 to the slaughter at Cannae on August 2, 216 B.C., Hannibal had killed or captured in battle somewhere between 80,000 and 100,000 legionaries, along with hundreds of the senatorial and knightly classes, including two consuls at the head of their armies and numerous ex-consuls in the ranks. In the space of twenty-four months a third of Rome’s frontline troops of more than a third of a million men of military age were to be killed, wounded, or captured in the bloodbaths at Ticinus, Trebia, Trasimene, and Cannae. Cannae, then, was no fluke.
After the Roman massacre at Cannae, Hannibal did not march on Rome—to the great dismay of military pundits, from his contemporary subordinate Maharbal (“you know how to win a battle, Hannibal, but not how to use your victory” [Livy 22.51]) to Field Marshal Bernard Montgomery. For the next fourteen years Hannibal would experience a seesaw series of victories and defeats inside Italy that had little strategic effect upon the course of the Second Punic War, until he was recalled to Carthage to save his homeland from the invasion of Scipio Africanus. Not far from Carthage itself at Zama (202 B.C.), Scipio’s legions defeated Hannibal’s veterans, and Carthage submitted to harsh Roman terms that essentially ended its existence as a military power in the Mediterranean. The city’s ultimate destruction was only a half century away (146 B.C.).
Hannibal, who had left Carthage for Europe in 219, had unknowingly been on a fruitless odyssey of some twenty years, a vast circuit across the Mediterranean, Spain, the Alps, and Italy that came to a close thousands of dead later where it had all begun—and with a Roman army once again free to march on Carthage itself. As the historian Polybius concluded of the Roman recovery after Cannae and its effect on the Carthaginians: “Hannibal’s pleasure in his victory in the battle was not so great as his dejection, once he saw with amazement how steady and great-souled were the Romans in their deliberations” (6.58.13).