13 greatest battles in Roman history

A battle's importance cannot be defined only by its size or death toll. Several factors influence its lasting impact on history. 

One factor is strategic value because it involves territory or resources at stake and the wider consequences of the battle’s outcome. 

In these cases, when a battle clearly shifts the balance of power between rivals, nations, or empires, it is recorded in history as a ‘turning point’ that changed the course of events. 

Another factor is that a battle's importance is influenced by the key figures involved, their choices and actions, and the lasting results of those actions. 

In particular, acts of bravery, new tactics, and critical mistakes on the battlefield can teach lessons for future generations. 

With those categories in place, let’s examine the most famous victories during the history of ancient Rome. 

The Battle of Lake Regillus was a major event in the early history of the Roman Republic, taking place around 496 BCE. 

The fight resulted from tensions between the new Roman Republic (which had removed its monarchy in 509 BCE) and the Latin League, an alliance of city-states in the region led by Rome's long-standing opponents, the Latin city of Tusculum. 

At the centre of this conflict was the ousted Roman king Lucius Tarquinius Superbus. He tried to regain his throne with support from the Latin League. 

Lake Regillus was near modern-day Frascati in the Alban Hills. 

The Roman army was led by the dictator Aulus Postumius Albus and his Master of the Horse, Titus Aebutius Elva, while the Latin League was led by the exiled Tarquinius Superbus, his son-in-law Octavius Mamilius of Tusculum, and other Latin leaders. 

The battle saw intense violence as each side suffered heavy losses. 

However, stories say that Rome received help from the gods Castor and Pollux. Their appearance on the battlefield raised Roman morale and led to victory. 

Due to the Roman victory, it ended Tarquinius Superbus’s attempts to regain his throne and confirmed Rome's independence from Latin control. 

It also paved the way for Rome's control over the Latin League and set the foundation for the later expansion of the Roman Republic.

The Latin League then signed the Foedus Cassianum, a treaty that set mutual defence obligations, but confirmed Rome as the top power in Latium. 

While many details of the battle are legendary, its importance for Rome's early history is clear. 

The Battle of the Allia happened in 390 BCE and between the Roman Republic and the Senones, a Gallic tribe led by their chieftain, Brennus. 

Before the fight, the Senones crossed the Alps and entered Roman land to gain territory and loot. The Allia River sat about 11 miles north of Rome. 

Roman military tribunes led the army there but the Gauls outnumbered them. 

Unfortunately, the Roman army made a serious mistake: they formed a thin line along the riverbank and left their sides open, and the Gauls noticed this. 

When the battle began, the Gauls took advantage of that weakness, attacked the sides, and defeated the Roman soldiers. Then they headed towards Rome. 

The Romans who survived had to fall back but the Gauls were able to sack the city. 

This defeat was a warning for Rome about the need for strong military organisation and the need to learn from their mistakes. 

The loss and the sack of Rome stayed was remembered by the Romans for generations.

In fact, the date of the battle, July 18, became known as dies Alliensis or 'Allia Day', which was seen as a bad sign in the Roman calendar. 

In 295 BCE, the Romans fought the Battle of Sentinum, a major engagement in the Third Samnite War (298 to 290 BCE) and an important turning point in their effort to control the Italian Peninsula. 

Near Sentinum in what is now Marche in Italy, the Roman army met a large enemy force. The Romans had about 36,000 men and faced around 40,000 opponents. 

At that point, the Roman army was organised into legions in a wide formation. 

During the fight, Decius Mus led the Roman left side, and it began to weaken under a strong attack. 

Under heavy pressure, Decius Mus carried out the devotio ritual, in which he dedicated himself and the enemy to the gods of the underworld. Then, he charged into the enemy ranks. 

This act energised the Roman troops. Soon, they regrouped and drove the enemy back. 

Following this victory, Rome kept expanding, eventually bringing the Samnites under control and holding the Italian Peninsula. 

The Battle of Cannae, fought on 2 August 216 BCE, continues to be one of the most well-known and studied military engagements in history. 

At that time, this large-scale confrontation took place during the Second Punic War (218–201 BCE). The Carthaginian Empire was led by General Hannibal Barca. 

Cannae, a small village in southern Italy, became the setting for this famous clash.

There, Consuls Lucius Aemilius Paullus and Gaius Terentius Varro commanded the Roman army, which significantly outnumbered Hannibal’s forces. 

Yet, it was Hannibal’s tactical skill that decided the outcome of the battle.

Specifically, he employed a tactic that has since become synonymous with his name: a double envelopment of the Roman army. 

He positioned his infantry in a crescent formation as the Carthaginian centre gradually pulled back under pressure from the Roman legions. 

As the Romans advanced, they exposed their flanks to Hannibal’s cavalry, which then performed a pincer movement, surrounding and trapping the Roman soldiers. 

Ultimately, the result was disastrous for Rome. The Roman army suffered an estimated 50,000 to 70,000 casualties, while Carthaginian losses were much lower.

Notably, those losses included 80 senators, nearly one-third of the Senate’s membership. 

However, despite Hannibal’s victory, it did not cause the collapse of the Roman Republic.

The Romans recovered and eventually won the Second Punic War thanks to the next battle on our list. 

In 202 BCE, near modern-day Tunisia, the Battle of Zama was the last phase of the Second Punic War (218–201 BCE) and ended the long conflict between Rome and Carthage. 

In that battle, General Publius Cornelius Scipio Africanus led the Roman Republic’s forces against Hannibal Barca’s Carthaginian army. 

Following his earlier successes in Italy, such as at Cannae, Hannibal returned to Africa to defend Carthage against Scipio’s forces. 

Carthage used terrifying war elephants, but Scipio arranged his maniples in a staggered formation to protect his men from these beasts. He let the animals pass through gaps without causing much harm. 

Next, Roman ally King Masinissa led the Numidian cavalry that drove off the Carthaginian horsemen and then attacked Hannibal’s infantry from behind. 

The defeat at Zama ended Hannibal’s military career and finished the Second Punic War. 

On Rome’s side, the victory strengthened Rome’s position in the Mediterranean and led to a treaty that took Carthage’s territories, forced them to accept a heavy payment, and forever limited the size of its army. 

As a result, Carthage never fully recovered. Rome destroyed the city in 146 BCE during the Third Punic War. 

In 168 BCE, the Battle of Pydna was an important fight in the Third Macedonian War (171–168 BCE) between Rome and Macedon. 

Roman legions, under Consul Lucius Aemilius Paullus, faced the Macedonian phalanx, led by King Perseus, son of Philip V. 

The battle took place near Pydna in Macedonia, now northern Greece. 

The Macedonian army formed a phalanx, a tight group armed with long spears called sarissas, whiel the Romans used a manipular formation, which focused on flexibility and movement. 

The rough ground broke the phalanx’s formation, creating gaps that Roman soldiers then used to attack. 

Afterward, the Romans inflicted heavy losses on Macedon and even captured King Perseus soon after. 

This victory ended the Third Macedonian War and brought Macedon under Roman control. 

Rome divided the region into four allied states. That action ended the Antigonid dynasty and the era of Hellenistic kings in Greece. 

In 48 BCE, in central Greece, the Battle of Pharsalus became an important moment in the Roman Civil War between Julius Caesar and Pompey the Great. 

Caesar’s forces were more than twice as small in the number of soldiers and horsemen deployed, but his plans and his troops’ experience made a difference. 

He placed his infantry in a tight formation and set a special unit on the flanks to guard against Pompey’s cavalry.

At the same time, he ensured his centre remained solid against any enemy charges. 

When fighting began, Caesar’s men held their ground and drove back the cavalry charge. 

Caesar then led a counterattack that broke Pompey’s centre and forced his army to flee. 

Following this, Pompey escaped to Egypt, where he was killed, leaving no rival to challenge Caesar’s authority. 

The Battle of Actium was fought on 2 September 31 BCE near the shore of Actium on the western coast of Greece. 

Octavian, who later became Augustus, the first Roman emperor, led a strong fleet under his admiral, Marcus Vipsanius Agrippa. This force formed the backbone of his strategy. 

Antony and Cleopatra’s forces included both Roman and Egyptian ships, but they would struggle to match Agrippa’s tactics. 

Antony’s fleet was larger, but its ships were slower than the smaller, faster Roman warships under Agrippa. 

When things went badly for Antony and Cleopatra, they fled with part of their fleet, and they hoped to reach Egypt. 

After their leaders left, the rest of their forces were quickly defeated by Octavian’s fleet, with only scattered units escaping. 

Antony lost over 200 ships, of which only 60 escaped to Egypt. 

Octavian then chased his rivals to Egypt, where Antony and Cleopatra took their own lives to avoid capture. 

The battle happened in the thick forests of modern Germany. A group of Germanic tribes, led by the Cheruscan nobleman Arminius, ambushed and destroyed three Roman legions under Publius Quinctilius Varus. 

Arminius had served in the Roman army and knew its tactics. He used this knowledge of the land to trap the Roman forces, and as a result, the ambush proved devastating. 

As the legions marched through the narrow forest paths, heavy rain slowed their progress, and their formations began to break down. 

Under these conditions, the Germanic fighters launched surprise attacks on the struggling legions. 

Because they were caught off guard and could not form a proper defence in the difficult terrain, the Roman forces were completely destroyed. 

The loss of the three legions and the capture of the legionary eagles dealt a serious blow to Rome’s reputation, and after the disaster, Rome abandoned future plans to cross the Rhine. 

As a result, the Battle of the Teutoburg Forest ended Rome’s attempt to conquer the Germanic tribes east of the Rhine River, setting the Rhine as the boundary between the Roman Empire and Germanic lands. 

The Battle of Watling Street took place in 61 CE and was an important fight between the Roman Empire and native Britons led by Queen Boudica of the Iceni tribe. 

The battle took place on Watling Street in what is now England and was the final stage of a revolt against Roman rule and the mistreatment of local people. 

Boudica led a revolt and managed to join several British tribes into a single army to form a larger fighting force. 

The rebels first won battles at Colchester, London and St Albans, and these early victories encouraged more Britons to join Boudica’s army, which may have grown to tens of thousands. 

Despite their larger numbers, the Britons faced a well-trained Roman force under Governor Gaius Suetonius Paulinus. 

Paulinus picked the battlefield with care by placing his troops with their backs to a forest so the Britons could not use their numbers all at once. 

When Boudica’s forces attacked, the Roman soldiers stood firm before launching a strong counterattack that broke the Britons’ line and caused a total defeat. 

The battle ended Boudica’s uprising and kept Roman rule in Britain. In terms of losses, some accounts say as many as 80,000 rebels died, while Roman losses were about 400. 

Ultimately, Boudica’s revolt did not succeed, but her courage and will to resist became a symbol of resisting Roman rule. 

The Battle of Abritus happened in 251 CE near the city of Abritus in modern Bulgaria.

This encounter was a major defeat for the Roman Empire and a low point in its fight against invading tribes during the crisis of the third century.

The empire faced political problems, money shortages and attacks from outside groups. 

To stop Gothic raids, Emperor Decius led his troops against the invaders under the chieftain Cniva. The Goths had crossed the Danube River and raided Roman settlements. 

When the Romans chased the Goths into muddy land near Abritus, they became stuck and vulnerable. The Goths then attacked from the sides and caused heavy losses. 

In the end, the Romans were beaten and Emperor Decius and his son Herennius Etruscus died in battle: a crushing defeat that shocked Rome. 

It was one of the first times a Roman emperor died in battle against a foreign enemy. 

After this, the Roman state made changes and reorganised its army to face new threats.

Notably, these reforms aimed to strengthen frontier defences and improve troop readiness. 

The Battle of the Milvian Bridge took place on 28 October 312 CE. It decided who would control the Western Roman Empire and saw the start of Christianity’s rise in Rome. 

The battle took place at the Milvian Bridge over the Tiber River near Rome, where Constantine the Great faced his rival Maxentius. 

Constantine, as Western Emperor, marched on Rome to challenge Maxentius. 

However, before the fight, Constantine saw a cross in the sky and the words “In this sign, conquer”, which he took as a divine blessing from the Christian God.

So, he then had the Christian Chi-Rho symbol painted on his soldiers’ shields. 

Maxentius met Constantine’s troops at the bridge, but Maxentius’s army was pushed back toward the Tiber.

Many soldiers who tried to cross the river drowned. Maxentius also drowned when his temporary bridge collapsed. 

After his victory, Constantine became sole ruler of the Western Empire and later of the entire Roman Empire.

Following that rise in power, Constantine adopted Christianity, which allowed the religion to grow and gain official support. 

The Battle of Adrianople was fought on 9 August 378 CE and was a severe defeat for the Roman Empire. 

The battle took place near the city of Adrianople (modern-day Edirne, Turkey) and saw the forces of the Eastern Roman Emperor Valens face off against an army of Gothic rebels led by the chieftain Fritigern. 

The Goths had taken refuge within the Roman Empire because of pressure from the Huns. 

Unfortunately, they were treated poorly by the Roman authorities, and this led to their uprising. 

The Gothic forces had formed an alliance with other barbarian tribes and this posed a major challenge to the Roman Empire’s eastern frontier. 

In response, Emperor Valens assembled an army to suppress the rebellion and restore Roman control. 

Eager to win before reinforcements from the Western Roman Emperor Gratian arrived, Valens rushed into battle against the Gothic forces. 

The Roman army was composed mainly of infantry, and was ill-prepared to face the Gothic army, which had a large heavy cavalry force as well as infantry. 

The Romans were unable to withstand the Gothic cavalry’s fierce attack, and their lines began to collapse. 

The defeat was deadly for the Romans, with most of the army killed. This included Emperor Valens himself. Some sources say that 20,000 out of 30,000 troops died. 

The heavy losses showed Rome’s weakness and encouraged other barbarian tribes to challenge Rome’s authority. 

The battle also signalled a shift in the balance of power between infantry and cavalry on the battlefield, with cavalry proving to be a key factor in the conflict. 

In the years after Adrianople, the Roman Empire continued to deal with internal conflicts and outside threats, leading to its decline and eventual fall.