The Battle of Cannae: The Art of Double Envelopment
The Battle of Cannae, fought on 2 August 216 BCE in the Apulian plain of southeastern Italy, is one of the most famous and most studied battles in the history of warfare. Hannibal Barca, the Carthaginian general who had marched his army across the Alps to invade Italy, won a crushing victory over a much larger Roman army, killing perhaps 50,000 to 70,000 Roman soldiers in a single day. The battle is the textbook example of the double envelopment — the tactic in which a smaller force attacks the center of a larger enemy, induces the enemy to push into the center, and then closes in on both flanks. The battle has been studied by every generation of military commanders since, and it remains the most celebrated example of tactical brilliance in the history of warfare.
This page is a complete guide to the Battle of Cannae. It explains the strategic background, the battle itself, and the legacy. It links back to the Punic Wars cluster, Hannibal Barca, and the Siege of Carthage.
The Strategic Background
The Battle of Cannae was the climax of the second year of the Second Punic War. After his crossing of the Alps, Hannibal had won two great victories against the Romans — at the Trebia in December 218 BCE and at Lake Trasimene in April 217 BCE. The Romans had been defeated in two major battles and had lost a huge number of soldiers.
In 216 BCE, the Romans decided to raise the largest army of the Republic and to put an end to Hannibal. Eight legions were raised, the largest Roman army ever put into the field, and the consuls for the year were the experienced Lucius Aemilius Paullus and the more aggressive Gaius Terentius Varro. The army was about 80,000 men, of whom perhaps 70,000 were Roman or allied infantry and 6,000 were cavalry. Hannibal’s army was perhaps 50,000 men, of whom about 40,000 were infantry and 10,000 were cavalry.
The two armies met in the Apulian plain near the town of Cannae, on the banks of the Aufidus River. The plain was flat and dry, ideal for the operations of cavalry. Hannibal chose the field of battle carefully: he positioned his army with the river at his back, so that the Romans could not outflank him on one side.
The Battle
The battle was fought on a hot August day. The Roman army, drawn up in the traditional formation, was much wider than the Carthaginian army. Hannibal drew up his army in a deep formation, with the center weaker than the wings. The center consisted of the Libyan and Iberian infantry, who were trained to give way gradually; the wings consisted of the Celtic and Iberian heavy infantry, who were to hold their ground.
The Roman infantry advanced and engaged the Carthaginian infantry. The Roman center pushed forward and the Carthaginian center gradually gave way, as Hannibal had planned. The Roman army pushed deeper and deeper into the Carthaginian center, with the result that the Roman line became longer and thinner, and the Roman wings moved forward to keep the line even.
Then Hannibal sprung his trap. The African heavy infantry on the wings, who had been holding their position, suddenly turned inward and attacked the Roman wings from the flank. At the same time, the Carthaginian cavalry, which had driven the Roman cavalry from the field, came around behind the Roman army and attacked the Roman rear. The Roman army was now surrounded on three sides, with the river at its back. The Roman infantry, however, did not break, and they continued to fight in the center.
The result was a massacre. The Romans, surrounded and unable to maneuver, were cut down where they stood. According to the ancient sources, the Roman losses were 50,000 to 70,000 men, including the consul Aemilius Paullus (the other consul, Varro, escaped with a small force of cavalry). The Roman army was effectively destroyed. The battle is considered the greatest single-day defeat in Roman military history, and it is one of the worst defeats ever suffered by a major state.
The Aftermath
The battle was a catastrophe for Rome. The southern Italian cities, including the great city of Capua, defected to Hannibal. The Greek city of Tarentum, the port of southern Italy, also defected. Hannibal was master of southern Italy, and the Romans were on the defensive.
The Roman response, however, was determined. The Senate refused to negotiate with Hannibal, and it appointed Quintus Fabius Maximus, the cautious general who had advocated a strategy of harassment, as dictator. The “Fabian strategy” of avoiding pitched battles and waiting for Hannibal to be worn down was adopted, and it eventually worked. Hannibal was never able to take Rome, never received the reinforcements he needed, and was gradually confined to a small area in the toe of Italy. The Romans counterattacked in Spain, Africa, and Sicily, and they eventually invaded Africa itself, forcing Hannibal to return home. He was finally defeated at the Battle of Zama in 202 BCE.
The Legacy of Cannae
The Battle of Cannae is one of the most studied battles in the history of warfare. The double envelopment — the tactic in which a smaller force uses its stronger center to give way, its stronger wings to hold, and its cavalry to attack the enemy from the rear — has been the model for tactical brilliance ever since. The battle has been studied by Napoleon, by Schlieffen, by Eisenhower, and by every generation of military commanders since.
The battle has also become a powerful metaphor. The phrase “Cannae” has been used to describe any decisive tactical victory. The German General Schlieffen planned the famous Schlieffen Plan of World War I as a kind of Cannae, with a sweeping envelopment through Belgium. The plan was based directly on Hannibal’s tactics, and it was the most ambitious application of the Cannae idea in modern history.
The Battle of Cannae is also a powerful symbol of the human cost of war. The Roman losses were enormous, and the battle set the Roman state back for years. The battle is a reminder that even the most brilliant tactical victory cannot win a war, and that the long, patient strategy of the Fabian general eventually wore down even the genius of Hannibal.