How Failure at the Battle of Cannae Nearly Destroyed the Roman Republic

By John Trumbull (1756-1843) - Yale University Art Gallery - The Death of Paulus Aemilius at the Battle of Cannae, Public Domain, https://commons.wikimedia.org/w/index.php?curid=40826676
March 2, 2020 Topic: History Region: Europe Blog Brand: The Buzz Tags: Battle Of CannaeRomeCarthageHannibalSecond Punic War

How Failure at the Battle of Cannae Nearly Destroyed the Roman Republic

A terrible loss.

Long ranks of Carthaginian infantry stood on a dusty plain a few miles east of the ruined town of Cannae on August 2, 216 bc. Cavalry massed at each end of the Carthaginian line stood poised to harass the enemy’s flanks. Opposite the Carthaginians, a Roman army was arrayed in similar fashion.

The day was warm, dry, and windy. A seasonal wind known as the libeccio, which blew from the south, sent fine particles of dust into the faces of the advancing Romans. The armies had deployed from their camps north of the River Aufidius to the south side of the twisting waterway.

As combat grew near, many of the Carthaginian troops gripped Roman weapons that they had picked up from a clash at Lake Trasimene the previous year. More than a few wore similarly looted Roman armor. They carried Roman javelins, spears, and gladii. None of them had seen their native lands for many years. Indeed, the only way they might ever see those homes again was to achieve yet another victory. Although outnumbered and deep in enemy territory, their confidence remained high.

The Carthaginian troops had complete faith in their stalwart leader, Hannibal Barca. Hannibal had proved that he was brilliant, bold, and daring. Upon the fields surrounding Cannae that day Hannibal’s name would become deeply etched in the annals of history. What Hannibal would achieve at Cannae would forever mark him as one of the greatest battlefield commanders of all time.

Rome and Carthage had previously gone to war against each other in the First Punic War that began in 264 bc. Over the course of the 23-year conflict, the Romans gradually wrested control of Sicily from the Carthaginians. The Carthaginians, who retreated to the western part of the island, could no longer sustain themselves when the Romans destroyed their fleet in the Aegates Islands in 241 bc. Rome ejected the Carthaginians from Sicily and forced them to pay a heavy indemnity at the peace table.

The Romans emerged from the First Punic War as the dominant naval power in the Mediterranean Sea. Afterward, the Carthaginians began to rebuild their military forces in anticipation of a new war. To finance their armies and fleet, the Carthaginians embarked on a concerted effort to expand economically.

Hamilcar Barca, one of Carthage’s leading generals, masterminded the Carthaginian occupation of Iberia. It took decades and a generation of the Barca family, but by 218 bcCarthage was ready to exact revenge against Rome. The job fell not to Hamilcar, but to his son, Hannibal. When Hannibal was only 10 years old, Hamilcar made him swear an oath of eternal enmity toward Rome.

Hannibal was an astute commander who knew how to inspire men. He once swam a river to encourage his men to follow and slept on the ground as they did. Ready for a rematch with Rome, Hannibal attacked the Iberian city of Saguntum after its leaders chose to ally with Rome. The incident touched off the Second Punic War.

Seizing the initiative, Hannibal led his army north. The Carthaginians crossed the Alps and invaded the Roman heartland with 46,000 troops and 37 elephants. Hannibal recruited Gauls and others enemies of Rome as he marched.

The Romans responded with their legions, each accompanied by another legion raised by a Roman ally in the region. Hannibal’s generalship brought the Romans low at Trebia in 218 bcand at Lake Trasimene in 217 bc. Rome suffered heavy casualties and damage to its reputation from these defeats.

The Romans needed to turn the tide. For that reason, they appointed Quintus Fabius Maximus as dictator. Fabius realized his best option was to create time to rebuild the Roman armies, so he avoided pitched battles and sought smaller skirmishes designed to weaken the Carthaginians gradually while building his own strength. While the strategy was reasonable given the situation, it did not sit well with Roman leaders. Rome had a tradition of aggressive military action and their mind-set precluded anything other than the offensive.

The Romans subsequently elected two consuls, Lucius Amelius Paullus and Gaius Terentius Varro. Meanwhile, the Roman Senate authorized the expansion of the Roman army by four legions along with four allied legions. These would join with two existing armies led by the previous year’s consuls, Marcus Atilius Regulus and Gnaeus Servilius Geminus. Regulus would be replaced before the battle by Marcus Minucius Rufus. These existing armies shadowed Hannibal’s force while it wintered in Geronium in southern Italy.

The Roman plan was simple. Paullus and Varro would each command the army on alternating days, a Roman custom of the time. They would rendezvous with the two armies in the field and take command of the entire force. Their objective was to bring Hannibal to battle and defeat him, thereby ending the Carthaginian threat. The alternating command may have been Roman tradition, but Paullus and Varro disliked each other and were frequently at odds. Thus, the Roman army had a significant leadership problem. 

The two armies were organized and equipped according to their own customs and heritage. The Roman legions were raised by the legio, a levy of citizens ranging from 17 to 49 years of age, who owned property. Rome had a long martial tradition and propertied families were accustomed to military service, training their sons for it.  In addition, each Roman ally was expected to raise its own legion to join the Romans on a one-for-one basis. It is believed these units were organized similarly to the Roman legions. During the Second Punic War the legions were raised for a period of one year with new troops rotated through them, so these units began to become permanently established organizations.

Each legion was 4,500 strong with 4,200 infantry and 300 cavalry. By this time the legions were organized into the triplex acies, a system of three lines. The first line was the hastati, 1,200 younger men armed with the pilum, a Roman javelin, and the gladius, a short sword. They also carried a large shield called a scutum and wore a helmet and chest armor. The second line consisted of the principes, another 1,200 men considered in their prime. They carried similar arms and armor to the hastati though some may have worn mail coats called lorica hamata. The third line held the triarii, 600 experienced older men who also carried spears. Each legion also had 1,200 velites, light infantry who would screen the legion and act as skirmishers. These men probably did not wear armor but carried a light shield, a few javelins, and a gladius. These lines would stagger to cover gaps, which also allowed the cavalry or velites to move through the formation more easily.

The wealthiest Romans made up the cavalry. Known as the equites, they guarded the flanks and pursued fleeing enemy soldiers. The 300 horsemen of a legion were divided into 10 turmaes of 30 men each, all well armed and armored. Generals often positioned themselves with the cavalry. In all a well-trained legion was a formidable unit led by trained leaders, the entire force steeped in the militaristic Roman tradition. One flaw of the legions present at Cannae was a lack of training. They were hastily raised and sent into battle before they could be seasoned. The troops also were raised from a wider group due to the desperate need for men after the previous defeats. The property requirements were eliminated, which meant many of the recruits lacked the martial training the wealthier men received.

The Carthaginian army followed different practices based on Carthage’s multicultural nature and experiences. Carthage did not have Rome’s population base and historically paid more attention to its navy. Their society was largely an oligarchy and the army reflected that quality. The Carthaginians drew troops from the various provinces and allied states to round out their army. The army contained a small core of citizen-soldiers surrounded by larger numbers of the allied troops and mercenaries recruited through Carthage’s extensive trading networks. The polyglot Carthaginian army was composed of Carthaginians, Numidians, Libyo-Phoenicians, Iberians, and Gauls. The Carthaginian cavalry at Cannae consisted of Numidians, Iberians, and Gauls. The senior officers were Carthaginians and were drawn from the city’s leading families.

Rather than try to train and organize these disparate factions along a common line, each contingent was allowed to fight according to its native traditions. This allowed the various groups to maintain their cohesion in battle, remaining at the side of their tribal comrades. They also used whatever equipment was familiar to them; however, as the campaign stretched out over the years much of the original equipment had to be replaced.

In combat, the Carthaginian infantry often would form into side-by-side columns to help maintain cohesion. This formation mitigated the differences in fighting techniques of the various contingents. These columns contained the Gauls and Iberians in alternating blocks with the Libyo-Phoenicians anchoring them on both ends. In front of this line of columns were the light infantry, which was composed of Balearic slingers and Celts. Four thousand Gallic horsemen were present in the Carthaginian army at the time of the battle. Like the Romans, they took their place on either end of the infantry formation, prepared to screen or charge as needed.