Written by Andoni Román Bañares
The Battle of Cannae, fought during the Second Punic War, is one of the most famous and studied battles in military history. It marked the peak of Carthaginian general Hannibal Barca’s tactical brilliance. On the plains near the Adriatic coast, Hannibal’s outnumbered forces crushed a massive Roman army, delivering one of the worst defeats Rome ever suffered.
Background:
Tensions between Rome and Carthage had been building for years. In response to Roman expansion, Carthage focused on growing its power in Hispania (modern Spain), a region rich in resources and manpower. In 226 BCE, Rome forced Carthage to sign the Treaty of the Ebro, which limited Carthaginian expansion north of the Ebro River. However, in 219 BCE, Hannibal attacked Saguntum, a Roman ally south of the Ebro. This triggered the Second Punic War.
Rather than fight Rome at sea or in Spain, Hannibal took the bold step of invading Italy itself. In one of the most daring feats in military history, he crossed the Alps with his army, including elephants. Although he lost many men during the journey, he arrived in northern Italy and won major victories at the Trebia (218 BCE) and Lake Trasimene (217 BCE).
In response, Rome appointed Quintus Fabius Maximus as dictator. Fabius avoided open battle and instead harassed Hannibal’s supply lines in a cautious strategy that came to be known as “Fabian tactics.” But many in Rome grew impatient with this approach. When Hannibal moved to threaten Cannae, a key Roman supply center near the Adriatic, the Senate decided to face him head-on.
The Armies:
The Roman consuls for the year, Lucius Aemilius Paulus and Gaius Terentius Varro, gathered Rome’s largest army yet – about 80,000 infantry and 6,000 cavalry. On August 2, 216 BCE, Varro was in command (the consuls alternated days). Despite Paulus advising caution, Varro decided to engage Hannibal directly.
The Romans positioned themselves between the Aufidus River and nearby hills, deploying 70,000 infantry in the center, flanked by 1,600 cavalry on the right (commanded by Paulus) and 4,800 allied cavalry on the left. A reserve force of 10,000 triarii remained in the camp. The Romans stacked their infantry extra deep, hoping to overpower the Carthaginians and breakthrough the center of their line.
Hannibal’s army was smaller, with about 40,000 infantry and 10,000 cavalry, including Numidians, Spaniards, and Celts. Aware of Rome’s preference for head-on attacks, Hannibal set a brilliant trap. He placed his weakest troops in a curved formation at the center, with his strongest forces – Libyans and Phoenicians – on the flanks. Hannibal’s strategy aimed to establish an “elastic defense,” absorbing the Roman thrust while enveloping their flanks. Hannibal also took advantage of the wind, arranging his troops so that dust would blow into the Romans’ faces. According to Livy, this was a decisive tactical advantage:
‘Hannibal had pitched his camp near the village, with the Volturnus wind at his back, raising clouds of dust across the parched plains. This phenomenon would prove advantageous, not only for the camp but also during battle formation, as the Carthaginians fought with the wind at their backs, against a blinded enemy.’ [Livy, The History of Rome, 22.43]
The Battle:
At first, things looked good for Rome. The legions pushed forward and began to collapse Hannibal’s center. But Hannibal wanted them to advance. As the Romans pressed deeper, the Carthaginian flanks held firm and then swung inward, wrapping around the Roman formation. Meanwhile, Hannibal’s cavalry had driven off the Roman horsemen and circled back to attack the Roman infantry from behind.
The Roman army was surrounded on all sides. With no room to maneuver and no cavalry support, the tightly packed Roman soldiers were cut down. According to Livy, 48,000 Romans were killed and 19,000 were taken prisoner. Carthaginian losses were minor by comparison.
Aftermath:
Cannae was a disaster for Rome, but a masterpiece of strategy for Hannibal. His use of double envelopment, surrounding and destroying a larger army, became legendary in military history. His cavalry played a decisive role, not just in defeating the Roman horsemen but in encircling the infantry.
Despite the crushing victory, Hannibal did not march on Rome itself, rendering Cannae a missed strategic opportunity. Instead, the battle served as a devastating moral blow and a lesson in humility for Rome. Varro’s overconfidence and reckless push for battle stood in contrast to Paulus’ caution.
Rome learned from its mistakes. It reformed its armies, improved its cavalry, and adopted more flexible strategies. These lessons helped Rome win later battles and ultimately defeat Hannibal at the Battle of Zama in 202 BCE, ending the Second Punic War.
Bibliography:
Sotto, Joaquín and Montes. (1961). “Cannae (The Perfect Battle).” Revista de Historia Militar, vol. 8, pp. 22-24.
Primary Sources:
Polybius: Histories, vol. I: Book III, Biblioteca Clásica Gredos, Tr. Balasch Recort, M., 2017.
Livy: History of Rome, vol. I: Books XXI–XXV, Madrid, Alianza Editorial, Tr. Ramírez de Verger, A., 1996.
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Cite this page as: The American Institute for Roman Culture, “The Battle of Cannae (August 2, 216 CE)” Ancient Rome Live. Last modified 6/17/2025. https://ancientromelive.org/cannae
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