Ancient Rome was a civilization forged in war. Between the fifth and first century BCE, Roman armies turned the small city-state on the banks of the Tiber into a leading power in the ancient Mediterranean and beyond. The Romans defeated the other peoples of Italy first, establishing themselves as the masters of the Apennine peninsula. But it was the war with Carthage that secured Rome’s predominant place in the western Mediterranean, allowing for further conquests. Finally, at the turn of the first millennium BCE, Roman legions subdued the once-mighty Hellenistic Kingdoms, becoming the undisputed great power of the ancient world. Not all these battles were victories. On the contrary, the Roman Republic counted many losses, often finding itself on the brink of destruction.
Yet, through its commanders’ leadership and well-disciplined citizen-soldiers, Rome always recovered, creating a powerful force that would build a mighty state. In the end, the Roman Republic’s builders — i.e., the generals and the army — toppled the state in a series of civil wars, ushering in an even mightier Empire. Here is a list of the five most crucial battles that (un)made the Roman Republic.
1. Cannae (216 BCE): The Roman Republic’s Darkest Hour
Among all Roman battles, both Republican and Imperial, Cannae occupies a special place. The very name evokes a sense of dread and respect for both sides involved in one of the deadliest battles in history. The Battle of Cannae was a masterpiece devised by Rome’s worst nemesis, the Carthaginian general Hannibal Barca. It was the apex of his famed Italian campaign, which began with the legendary crossing of the Alps. While Hannibal won two splendid victories on Rome’s home turf, at Trebbia and Trasimene, it was at Cannae that he would humiliate his enemy, dealing the Romans one of their greatest defeats.
In the summer of 216 BCE, fresh from his recent victories, Hannibal marched into southern Italy, where he captured a vital supply depot near the town of Cannae. Unsurprisingly, the hostile takeover of the fertile land filled with great estates belonging to prominent senators caused an uproar in Rome. Although it was producing results, Rome’s scorched-earth policy was abandoned in favor of the one decisive battle. To fight the Carthaginian menace, the Senate raised the largest army of the Roman Republic. Estimates of the numbers vary, but it is reasonable to assume around 60 to 70,000 men were divided into eight legions. The command of this massive formation was given to two newly elected consuls: Lucius Aemilius Paullus and Gaius Terentius Varro, who immediately departed for Cannae.
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On the morning of the 2nd of August, the two armies assembled on a hot, dust-blown plain and prepared for the decisive showdown. Varro (who was in command that day) drew a battle line on the south bank of the Aufidus river. It was a traditional Roman formation, with heavy infantry in the center, protected by the cavalry on both wings. Hannibal, on the other hand, opted for an unconventional approach. He placed light infantry in the center while his veteran heavy foot soldiers held the flanks. The Romans held a favorable position and had larger numbers but lacked Hannibal’s tactical brilliance, which would soon prove to be their undoing.
From the very start, Hannibal took the initiative. First, his horsemen charged at the Roman cavalry, chasing them off the battlefield. Then, the general ordered the retreat of Carthaginian infantry, allowing the Romans to pursue. However, the retreat was a ruse. The Roman legionaries, slowly moving forward, became drawn into a retreating line of hostile light infantry. It was the moment Hannibal was waiting for. His heavy troops closed from the sides while the horsemen (who had returned from the chase) charged into the rear of the tightly packed Roman formation. Yet, the corralled legionaries showed no sign of surrender. Most of the soldiers, stuck in the middle, unaware of their impending doom. Crammed like sardines, the soldiers lost their ability to maneuver or use their weapons. The result was a massacre never seen in Roman history. When the moon rose above the battlefield, more than 50,000 soldiers were lying dead. Most of the officers perished in the battle, including Paullus.
Those lucky few who escaped were not in a position to fight. Nothing stood between Hannibal’s army and the city of Rome. Yet, in their darkest hour, the stubborn Romans refused to yield. Instead of laying down the arms, the Roman Republic fought on. Lessons learned from the battle, paired with stubbornness and pride, would eventually result in Rome’s total victory and undisputed mastery of the Mediterranean and Carthage’s destruction.
2. Zama (202 BCE): The Dawn of a Great Power
The Second Punic War began auspiciously for Carthage. Hannibal Barca caught the Romans totally by surprise, defeated them on their home turf, and crowned his victory with the bloody masterpiece of Cannae. However, his greatest triumph had sown the seeds of his defeat. Weakened by constant fighting and the Roman scorched-earth policy, Hannibal’s army slowly withered away. Carthage, scared by Hannibal’s growing influence, sent no additional troops. The only reinforcement attempt, led by his brother Hasdrubal, failed following the defeat of the relief army in the battle of Metaurus in 207 BCE.
While Hannibal lingered in Italy, the Romans went on the counteroffensive, striking directly at the center of Barcid power in Spain. The leader of the Roman army was a young general named Publius Cornelius Scipio. Incidentally, he was one of the few higher-ranking survivors of Cannae. Using lessons from Rome’s defeat, Scipio adapted Rome’s strategy and tactics, pushing Carthage out of Spain. Finally, in 204 BCE, the time had come for the Roman Republic to strike back. Scipio landed on the shores of North Africa with 26,000 men and invaded Carthage itself.
Having no other choice, Carthage recalled its best general home. In 202 BCE, Hannibal and Scipio met on the field of battle near Zama. Hannibal’s battle-hardened warriors were reinforced by less experienced African troops, leaving him in command of around 45,000 men. For the first time in the war, Hannibal could not count on elite Numidian cavalry since most of them had joined the Roman side. Scipio, on the other hand, commanded around 35,000 soldiers. The vast plain allowed for the employment of the Carthaginian’s most deadly weapon — war elephants. Hannibal had 80 mighty beasts, which he hoped would turn the battle in his favor.
The battle commenced with the elephant’s charge into the ranks of the Roman heavy infantry. However, crafty Scipio had arranged his small and flexible units in columns, the gaps masked by light infantry. Thus, instead of charging into the Roman troops, the beasts passed harmlessly through the lines, leaving the battlefield. With the elephants out of the picture, Scipio’s experienced legionaries quickly dispersed the inexperienced Carthaginian foot soldiers. Only Hannibal’s Italian veterans proved equal to the legionaries, offering fierce resistance. However, when Scipio’s cavalry, which had driven off Hannibal’s horsemen, returned to charge the veterans from the rear, the enemy’s line broke up, resulting in a general rout.
With its last army annihilated, Carthage had to sue for peace, accepting humiliating terms. Hannibal Barca, whom Rome once feared, became a fugitive, eventually committing suicide in 182 BCE. Carthage was now reduced to a Roman client state until its destruction in 146 BCE. The victory over its greatest rival laid the foundation for the Roman Republic’s expansion into Africa and Asia and its mastery over the Mediterranean. Yet, it had also sown seeds of its downfall. The emergence of a professional army that was not only loyal to the Senate but also to its commanders would eventually result in civil wars that would tear the Republic apart.
3. Carrhae (53 BCE): The Curse of the East
The victory over Carthage left Rome as the major Mediterranean power. In the following decades, Rome gradually expanded East, taking control over Greece and then pushing into Hellenistic Asia Minor. By the mid-first century BCE, the Roman legions reached the Persian frontier, setting in motion a conflict that would last for more than half a millennium. The Syrian-Mesopotamian frontier would become the battlefield for the two mighty Empires.
The conflict opened in 53 BCE when Marcus Licinius Crassus led an army to attack Persia, which was ruled by the Parthian Empire. Crassus was the wealthiest man in Rome and one of three leading men of the Roman Republic. However, unlike his peers, Julius Caesar and Pompey the Great, Crassus achieved no military glory. Persia was the place where he hoped to score his greatest victory, making him equal to Alexander the Great, the legendary conqueror. Little did he know that he would be only the first of many Roman commanders and leaders who would find doom in the East instead of everlasting fame.
Crassus entered Persia at the head of the mighty army of seven legions, around 40,000 strong. The 62-year-old commander expected an easy victory as the Parthian’s strength had been weakened by an internal struggle. Furthermore, the Romans had little regard for the Parthians as a rival. Perhaps that was the reason why Crassus refused the offer of his ally, the Armenian King Artavasdes, for additional reinforcements. However, unbeknownst to the Romans, they were marching into a trap. Once the army reached a desolate part of the Syrian desert, the enemy attacked in force.
Although the Parthians were vastly outnumbered by the Romans, having around 10,000 men, they possessed something that the Romans sorely lacked. Their army consisted almost entirely of cavalry, better suited to desert warfare than the Roman heavy infantry. Most were well-trained mounted archers. However, the Parthians also had a secret weapon, a unit the Romans simply could not match; their infamous heavily armored cavalry, the kataphraktoi. When Crassus met the enemy, he panicked. Instead of drawing up the traditional Roman battle formation — the heavy infantry in the center and cavalry on the wings — the man who possessed no military experience ordered his legions to form a large, tightly packed hollow square.
Such a strategy offered a degree of protection to the Romans, but it also significantly limited the mobility and flexibility of the legionaries. Crassus and his commanders could only helplessly watch as the Parthian horsemen galloped around the square, shooting a hail of arrows into the helpless Roman foot soldiers.
Whenever the Romans tried to engage, the mounted archers rode off at speed and lost shots as they withdrew. The fire of their composite bows was powerful enough to pierce armor. Every time the Romans broke out of their formation, the kataphraktoi would charge at full speed, killing the exposed legionaries. The Parthians had an almost endless supply of deadly projectiles, supplied by 1,000 camels. After his son Publius died in a doomed cavalry charge, Crassus requested a ceasefire to save what was left of his army.
During the parlay, a fight broke out, either planned or accidental, giving the Parthians cause to murder Crassus and his officers. The infamous story of Crassus being executed by having molten gold poured down his throat is probably a rumor. However, Crassus’ failure at Carrhae had much more disastrous consequences that went beyond a heavy loss of manpower and a blow to Roman prestige. With Crassus removed from the political arena, his two remaining allies, Caesar and Pompey, were put on a collision course, which would plunge the Roman Republic into a bloody civil war. Its outcome would topple down the old order and usher in the Imperial era.
4. Alesia (52 BCE): Caesar’s Path to Power
In 53 BCE, the same year Crassus met his violent end in the sands of Persia, a rebellion broke out among the Gauls, threatening to undo the conquests of his ally, Julius Caesar. For years, Caesar’s legions fought a series of bloody battles, resulting in the subjugation of the whole of Gaul. Instead of surrendering to the Roman army, the charismatic Gallic chieftain Vercingetorix dared to defy the great general. He united the warriors from central and western Gaul into a disciplined army that matched the Romans in willpower, if not in numbers. After months of bitter fighting, in Summer 52 BCE, Caesar cornered Vercingetorix and his 80,000 men on the high ground outside of Alesia.
Instead of opting for a costly frontal attack on the Gallic positions, Caesar ordered his 55,000-strong army to build an imposing fortification system. Twenty-three forts, linked by ditches and a rampart mounted by a palisade with towers at intervals of 25 meters (82 feet), prevented the enemy from escaping Alesia. However, before this astonishing line was complete, Vercingetorix’s cavalry managed to break out, suffering heavy losses in the process. Suspecting that the cavalry had been sent to organize a relief effort, Caesar ordered another ring of fortifications facing outwards to secure the Roman positions from the external attack.
As food ran out, the Gauls sent their women, children, and old people out of the town. Caesar, however, refused to let them through the Roman lines, condemning the hapless civilians to a slow and painful death from starvation in no man’s land. The siege was in its third month when, as Caesar had anticipated, a large Gallic relief force arrived. Three times they made an assault on the Roman siege line, each time assisted by the sortie from Alesia. Yet, each of the three attempts failed, although the last attack came close to success. In the end, the Roman defenses held fast.
Realizing that the battle was lost, Vercingetorix rode down to the Roman camp. He surrendered by laying his sword at Caesar’s feet. However, the powerful general was not in a forgiving mood. Each Roman soldier received a Gaul to sell into slavery. Humiliated, Vercingetorix spent six years languishing in a Roman prison. In 46 BCE, Caesar finally celebrated his triumph, delayed by the civil war. Vercingetorix was led in chains through the streets of Rome and then executed. The siege of Alesia marked the end of Julius Caesar’s Gallic campaign. Gaul was now a Roman province, and it would remain an important part of the Empire for five centuries.
Caesar’s thirst for ultimate power led him into open conflict with the Senate, and his main rival, Pompey the Great. The bloody civil war tore the Republic apart, leading to the battle of Pharsalus in 48 BCE. Caesar’s victory over the Pompeian troops, and his rival’s subsequent death in Alexandria, left him in sole control of the Roman world. However, his rule as dictator did not last for long. In 44 BCE, Julius Caesar was assassinated in a Senatorial plot, which led to another civil war, and ultimately brought death to the Roman Republic.
5. Philippi (42 BCE): The End of the Roman Republic
From the moment Julius Caesar uttered his famous words and crossed the Rubicon, the Roman Republic was set on the path of no return. Even Caesar’s assassination could not turn the clock back. The conspirators eliminated the dictator, but they had failed to get rid of his heir Octavian and his friend Mark Antony. After taking control of Northern Africa, in September 42 BCE, the two allies led an army into Macedonia to deal the final blow to the Republican force encamped at Philippi.
The outcome of the war, however, was not yet certain. The opposing forces were equal in strength, each fielding around 100,000 men. The immense numbers signaled the importance of the impending battle. However, the Republican leaders — Marcus Junius Brutus and Gaius Cassius Longinus — were reluctant to join combat. They had all the advantages of a good defensive position, as their legions were entrenched in a gap between an impassable marsh and untraversable hills. Secure in the two elevated fortified camps, Brutus and Cassius could bide their time, waiting for their superior navy to cut off the enemy’s supply line to Italy.
However, the Republicans failed to consider their opponent’s resolve and ingenuity. Aware of the unfavorable situation, Antony took the initiative and crossed the marshland undetected, by building a causeway. Mark Antony was in sole command of the attacking army, as before the battle, Octavian had fallen ill and remained in his camp. Cassius realized the danger, but he reacted too late. Antony’s men stormed Cassius’ fortifications, taking control of the enemy’s camp. Meanwhile, Brutus’ troops launched an attack on Octavian’s camp, completely surprising his legions. The severity of the situation was reflected by Octavian’s last-minute escape from his tent. However, due to the sheer size of the battlefield and communication difficulties, this information passed unnoticed by Cassius. Believing all was lost, the Republican commander committed suicide.
With casualties on both sides, the opposing armies remained in position. Three weeks later, suffering serious supply issues, Brutus decided to risk a pitched battle. It was a disastrous decision. While Octavian kept Brutus occupied from the front, Antony once more led his men through the marshes to envelop the Republicans’ left. The close-quarter infantry battle that ensued was bloody on both sides; however, Brutus’s men broke first. Brutus fled from the battlefield but soon followed Cassius’ example and fell on his sword. His army surrendered, leaving the Roman Republic in the hands of two victors — Octavian and Mark Antony.
The peace would not last for long. A decade after Philippi, Octavian defeated Antony at Actium, becoming the sole ruler of the Roman world and the first Roman emperor, Augustus.