In 216 BC Rome mobilized a force of 86,000 legionaries and auxiliaries under consuls Lucius Aemilius Paullus and Gaius Terentius Varro and sent them against some 50,000 men under the great Carthaginian general Hannibal. The Roman consuls alternated their daily command, and Varro was in charge on the day of battle.
As the battle opened, the Carthaginian cavalry overpowered and scattered the inferior Roman cavalry on the legions’ right flank. The Carthaginians then rode around the Roman army to destroy the cavalry on the legions’ left flank, which was skirmishing with the Numidian light horse. The Roman right flank promptly disintegrated, allowing Hannibal’s brother, Hasdrubal, to turn his heavy cavalry against the rear of Rome’s legions.
Meanwhile, the Roman infantry had advanced against Hannibal’s center, which yielded (without breaking) before the onrush of the numerically superior Roman forces. Slowly giving ground, Hannibal’s forces drew the Romans into a deep convex while his Libyan infantry stood fast on the flanks. Eventually the Carthaginian forces overlapped the Roman line and closed in on the seemingly victorious legionaries, who were on the verge of cracking Hannibal’s line. Hasdrubal’s cavalry charge from the rear sealed the legionaries’ doom.
Attacked from all sides by cavalry and infantry with short swords, the Romans pressed together, finding it impossible to properly wield their weapons. Many fought on in desperation until the army was virtually annihilated. Only one in eight legionaries on the field that day ever returned to Rome. The republic had suffered the worst military defeat in its history. The Second Punic War dragged on for another 14 years before the Romans finally defeated Hannibal, breaking Carthaginian military power for all time.
- Do not commit your major field army to a decisive battle against an army commanded by a military genius.
- Never leave a budding military genius and sworn enemy alive (three times) to wreak his vengeance on you at a later date.
- Before you enter into a war, have a long-range postwar strategic plan and the means to enact it once your army has won a decisive victory. After Cannae there was nothing standing between Hannibal’s victorious Carthaginians and the city of Rome, but having neglected to bring or build a siege train, Hannibal had no practical way to take Rome.
- It is not a good idea to make war on a state possessing almost inexhaustible reserves of manpower to fill decimated legions. As many others over the next half millennium were to learn and relearn, when you warred against Rome, you were making a serious wager about your future as a viable society. Rome never forgot, never forgave and, most important, never stopped coming on.
- For a trading nation whose economic well-being is directly tied to overseas international trade, it is a good idea before declaring war to build a navy that can command or at least contest control of the seas. Carthage didn’t rebuild its fleet following the First Punic War, so throughout the Second Punic War, Rome readily controlled the Mediterranean.
- Even the best infantry in the world (and the legions were by every measure superior to Hannibal’s troops) can be readily defeated by a well-handled, integrated combined force.
- Cavalry or a highly mobile striking army is a critical asset in battle. This was the one lesson the highly adaptive Romans never did seem to learn, as their history is replete with stories of legions lost for want of efficient cavalry.
- A single commander in chief provides infinitely superior leadership to that of co-commanders or an otherwise diffuse command structure.
- Finally, and most important, never let your army be caught in a double envelopment and then get surrounded. Only in very rare circumstances does anything good come of that.
Originally published in the May 2007 issue of Military History. To subscribe, click here.