"Rome, thou art punished now for having put Varro in command while Fabius still lived."

The Death of Aemelius Paulus by John Trumbull (1743). Click to enlarge.

The second day of August marks the darkest day in ancient Roman history. On that day, in 216 BC, the Roman legions under Gaius Terentius Varro and Lucius Aemilius Paulus were utterly crushed by the smaller army of Hannibal, grand general of Carthage, at Cannae in southern Italy.

The Battle of Cannae, one of the epochal battles of ancient history, was the climax of a series of victories won by Hannibal during his bold campaign in Italy. The Romans suffered over 40,000 killed out of an original force of about 80,000, with thousands more captured and turned to desertion. The consul Aemilius Paulus was also killed, and the scale of the disaster was so great that a panic ensued in Rome.

The most famous account of the battle is probably that of Titus Livius (Livy) written about 200 years after the fact. More contemporary is the account of the Greek historian, Polybius, written in the 2nd century BC, which was very likely Livy's main source for the battle.

Polybius explained how the Roman army followed Hannibal, who had taken the Roman supply depot of Cannae in Apulia, about 200 miles from Rome. The ground around Cannae is a broad flat plain, perfect for deploying Hannibal's superior cavalry forces. Recognizing his disadvantage, the consul Aemilius Paulus recommended a strategy of shadow and delay. Sadly, these types of tactics, made famous by the previous consul Fabius Maximus Cunctator (The Delayer), were in disrepute. The Romans demanded action—a decisive victory over the invaders—and Paulus's colleague as consul, Varro, would give it to them.

Polybius describes the discord between the two consuls, as Paulus resists the urge to battle, while Varro is irked by the inaction:

[Hannibal] drew out his men along the bank of the river [Aufidus], and showed that he was eager to give the enemy battle. But Aemilius, dissatisfied with his position, and seeing that the Carthaginians would soon be obliged to shift their quarters for the sake of supplies, kept quiet in his camps, strengthening both with extra guards. After waiting a considerable time, when no one came out to attack him, Hannibal put the rest of the army into camp again, but sent out his Numidian horse to attack the enemy's water parties from the lesser camp. These horsemen riding right up to the lines and preventing the watering, Gaius Terentius [Varro] became more than ever inflamed with the desire of fighting, and the soldiers were eager for a battle, and chafed at the delay. For there is nothing more intolerable to mankind than suspense; when a thing is once decided, men can but endure whatever out of the catalogue of evils it is their misfortune to undergo.

Having received command of the army on the following day, Varro promptly marched the legions out to fight. Polybius gives the following order of battle:

...Gaius Terentius got the army in motion from both the camps. Those from the larger camp he drew up in order of battle, as soon as he had got them across the river, and bringing up those of the smaller camp he placed them all in the same line, selecting the south as the aspect of the whole. The Roman horse he stationed on the right wing along the river, and their foot next them in the same line, placing the maniples, however, closer together than usual, and making the depth of each maniple several times greater than its front. The cavalry of the allies he stationed on the left wing, and the light-armed troops he placed slightly in advance of the whole army, which amounted with its allies to eighty thousand infantry and a little more than six thousand horse. 

At the same time Hannibal brought his Balearic slingers and spearmen across the river, and stationed them in advance of his main body; which he led out of their camp, and, getting them across the river at two spots, drew them up opposite the enemy. On his left wing, close to the river, he stationed the Iberian and Celtic horse opposite the Roman cavalry; and next to them half the Libyan heavy-armed foot; and next to them the Iberian and Celtic foot; next, the other half of the Libyans, and, on the right wing, the Numidian horse. Having now got them all into line he advanced with the central companies of the Iberians and Celts; and so arranged the other companies next these in regular gradations, that the whole line became crescent-shaped, diminishing in depth towards its extremities: his object being to have his Libyans as a reserve in the battle, and to commence the action with his Iberians and Celts.

The battle commences with skirmishes of the light troops on both sides, but develops quickly as the core Roman legionnaires aggressively advance into the Carthaginian center. Here is Polybius's account of Hannibal's famous pincer movement which led to the complete envelopment and destruction of the Roman army:

The legionaries took the place of the light-armed and closed with the enemy. For a short time the Iberian and Celtic lines stood their ground and fought gallantly. But, presently overpowered by the weight of the heavy-armed lines, they gave way and retired to the rear, thus breaking up the crescent. The Roman maniples followed with spirit, and easily cut their way through the enemy's line...

The Romans, however, going in pursuit of these troops, and hastily closing in towards the center and the part of the enemy which was giving ground, advanced so far, that the Libyan heavy-armed troops on either wing got on their flanks. Those on the right, facing to the left, charged from the right upon the Roman flank, while those who were on the left wing faced to the right, and, dressing by the left, charged their right flank, the exigency of the moment suggesting to them what they ought to do. Thus it came about, as Hannibal had planned, that the Romans were caught between two hostile lines of Libyans—thanks to their impetuous pursuit of the Celts.

Aemilius Paulus attempted to break the encirclement with a cavalry charge, but his forces were driven off by the heavy Carthaginian horse, and Paulus himself was killed. The result, for the encircled legions, was carnage:

As long as the Romans could keep an unbroken front, to turn first in one direction and then in another to meet the assaults of the enemy, they held out; but the outer files of the circle continually falling, and the circle becoming more and more contracted, they at last were all killed on the field—and among them Marcus Atilius and Gnaeus Servilius, the Consuls of the previous year, who had shown themselves brave men and worthy of Rome in the battle. While this struggle and carnage were going on, the Numidian horse were pursuing the fugitives, most of whom they cut down or hurled from their horses; but some few escaped into Venusia, among whom was Gaius Terentius, the Consul, who thus sought a flight, as disgraceful to himself, as his conduct in office had been disastrous to his country.

Hannibal Barca counting the
rings of the Roman knights killed 
at the Battle of Cannae, 
by Sébastien Slodtz (1704).

Writing in the 1st century AD, the Roman poet Silius Italicus (in his Punica) puts this lament into the mouth of Gaius Terentius Varro as he realizes the extent of the catastrophe:

“Rome, thou art punished now for having put Varro in command while Fabius still lived. But what means this divided mind, this change of fortune? Is it a trap laid for me by the Fates? I long to make an instant end of all things by taking my own life. But some god arrests my sword and keeps me alive that I may suffer even worse. Can I live and carry back to Rome these rods, broken and spattered with the blood of citizens? How shall I show my hated face through the towns of Italy? How shall I, a fugitive from battle, see Rome again? Hannibal himself could desire for me no more cruel punishment.”

In the face of this disastrous defeat, Hannibal expected the Romans to desire terms of peace. Though alarm and panic seized the city after the scale of the loss became known, the Romans quickly returned to steely resolve. Silius Italicus relates the Roman response:

But the senators and Fabius put sorrow in the background and turned quickly to other tasks. Slaves, chosen for their strength, were armed in haste….They were determined to bring, by any agency, the realm of Aeneas back to the land of the living, and to arm even bondsmen in defense of the Capitol….They took off from their own children the purple-bordered garment of boyhood and put armor on unaccustomed shoulders. Boys hid their faces behind the helmet, and were bidden to reach manhood in slaughter of the foe.

Likewise, when they were begged to ransom at an easy rate the multitude of Roman prisoners—and the number of petitioners rose to many thousands—they persisted, to the astonishment of Hannibal, in their refusal to redeem them. For they held it worse than any misdeed or any crime for an armed man to surrender….Such was the Rome in those days. And if it was fated that the Roman character should change when Carthage fell, would that Carthage were still standing!

As a result of the Roman defiance and determination to continue the fight, Hannibal was unable to follow up on his greatest victory. With the re-emergence of the Fabian strategy of delay, Hannibal found himself stymied in Italy, unable to properly besiege the city of Rome with the troops he had at hand. This gave the Romans time to recruit new legions, and make progress against Carthaginian strongholds and allies outside of Italy.