War: A History in 100 Battles. Richard Overy

       2. BATTLE OF CANNAE

      2 August 216 BCE

      The Battle of Cannae is one of the most famous battles of all time. The catastrophic defeat of the Roman army by Hannibal’s smaller force has been regularly invoked to describe a particularly dramatic or heavy defeat. The myth that surrounded Hannibal as a general who carried victory with him wherever he went has lived down the ages. Hannibal’s own presence at Cannae and his operational genius explain an outcome that might well have gone another way.

      The North African empire of Carthage dominated present-day Libya, Tunisia, Algeria and areas of conquest as far as Spain. The rising might of Rome in the third century BCE challenged Carthaginian ambitions and led to a series of Punic Wars between the two rival powers. In the second of these, at some point in 218 BCE, Hannibal persuaded the Carthaginian senate to let him set off on an epic journey across Spain, present-day France and over the Alps into Italy. What his ultimate objective was remains unclear, but he took with him an invasion force of probably 100,000 men, many of them Spanish mercenaries, and a huge train of supplies and animals, including his famous elephants. The journey itself undermined the scale of his ambitions. By the time the Alps were reached, he was down to 50,000 men; after crossing the mountains in autumn snow, he arrived in the northern Po Valley with only 20,000 foot soldiers and 6,000 cavalry to invade the Roman heartland. Bolstered by Gauls who joined his cause, Hannibal meted out heavy defeats on the Roman armies sent north to intercept him. As he moved south, Rome was gripped by panic. Hannibal’s military reputation inflated the threat out of all proportion. Lacking a secure base, living off the land, and not entirely sure of his Gallic allies, Hannibal chose to inflict on Rome what damage he could while himself avoiding defeat.

      In 216 BCE, Hannibal moved into Apulia in south-central Italy and in June that year set up his camp at the hilltop city of Cannae, guarding the route to the rich grain-lands of the south. The Romans had begun to create a force to eliminate the threat from the invader. Four new legions were raised, bringing the Romans’ strength to around 40,000 men with 40,000 allied soldiers, but only a small number of experienced cavalry. The two Roman consuls for 216 BCE, Gaius Terentius Varro and Lucius Aemilius Paullus, led the new army south to meet Hannibal, whose forces they probably outnumbered by two to one. At the beginning of August, the Roman army arrived at the flat plain in front of Cannae. As was customary, the consuls took turns to command on alternate days; Varro was the more audacious and on 2 August 216 BCE he led his force, spread out over nearly a mile, onto the plain to do battle. Accounts of the battle suggest that the infantry were packed between fifty and seventy ranks thick. The Roman cavalry were on one wing and the allied cavalry on the other, with a river protecting one flank. Roman battlefield strategy was to smash the enemy by sheer weight of numbers.

      At Cannae, Hannibal showed his exceptional grasp of the battlefield. He formed his infantry into a shallow force, weaker in the centre, with his veteran Libyans on both flanks. On one wing were Numidian cavalry, on the other Spanish and Gallic, 10,000 experienced horsemen who greatly outnumbered the 6,000 Roman horses. His infantry were ordered to form a bulge outwards with the object of enticing the Roman legions into the arc, which would then bend inwards, giving the wings the chance to encircle and annihilate the enemy while the cavalry defeated the enemy horsemen and turned to attack the Roman army from the rear. It was a textbook operation and functioned like clockwork. The Romans pressed forward into the yielding arc, only to find themselves surrounded as the Libyan infantry advanced on the flanks. The Carthaginian cavalry swept aside Rome’s horsemen and plunged into the Roman rear. Cannae was a massacre, the worst defeat the Roman army ever suffered. An estimated 50,000 died that day; others were taken prisoner. Only 14,500 survived out of an army of 80,000. Hannibal lost 6,000, two-thirds of them Gauls. No effort was made to bury so many dead, which included Paullus and eighty Roman senators. The gold rings and ornaments were collected from the dead and sent to Carthage to show the extent of the victory and to demonstrate the need for reinforcements.

      Hannibal could perhaps have marched on Rome and brought the empire to its knees. The disaster at Cannae left the city briefly defenceless, though new legions were immediately raised. The Senate ordered that there should be no weeping, and buried two Greeks and two Gauls alive to propitiate the gods. But Hannibal perhaps sensed that his depleted force was not large enough to march the 500 kilometres (300 miles) to Rome and to invest the city. Carthage was too busy fighting in Sicily, Spain and Sardinia to send help, so Hannibal undertook limited campaigns in southern Italy for a further fourteen years, too dangerous an opponent for the Romans to challenge again. To scare the citizens, he took 2,000 cavalry up to the gates of the city in 212 BCE, but could not risk a siege.

      When Hannibal’s brother Hasdrubal came to join him in 207 BCE by the same awkward route over the Alps, his forces were devastated near present-day Rimini and Hasdrubal was killed. Carthage was undermined on every front except in the south of Italy, where Hannibal was isolated. In 202 BCE, he finally left Italy for good to return to Carthage. A battlefield genius, he did not know how to win the war.