Julius Caesar's brutal conquest of Gaul explained

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Julius Caesar's Gallic Wars were some of the most important events in the late Roman republic, and they shaped the course of western Europe for centuries to come. Caesar's victory over the Gauls was impressive, and it solidified his status as one of Rome's greatest generals.


The Gallic Wars were a series of military campaigns fought by the Roman republic between 58 BC and 51 BC.


The wars were fought in an effort to expand the territory of the republic, as well as to subdue the rebellious Gauls who had been a strategic concern to Rome for centuries.


Caesar was tasked with leading the Roman legions against the Gauls, and he did so with great success.


After eight years of fighting, Caesar emerged victorious and established Rome's dominance over Gaul.

Historical context

The relationship between Rome and Gaul can be traced back to the time of the Roman Republic's founding in 509 BC.


Various Gallic tribes inhabited the region that is now modern France. The Gauls had been bothering Rome for centuries, raiding their settlements and pillaging their land.


In 390 BC, a Gallic army from northern Italy had even captured and sacked Rome. This event traumatised the Romans and it remained in their collective memory for over two centuries.


In 60 BC, there were two different regions that were called 'Gaul' by the Romans. One, called 'Cisalpine Gaul' was the region of northern Italy around the Po River.


This region had been conquered by Rome centuries before and was a province of the republic. Every year, Roman politicians were assigned as governors of this region.


The second region was called 'Transalpine Gaul', and it was the region that is roughly modern France today.


The Romans had previously established a province called Gallia Narbonensis, which was a part of Transalpine Gaul, in 121 BC, but most of this region had never been conquered by Rome.


No Roman army had successfully attempted to subdue the region and some fear still remained about what Gallic armies were capable of.

Looking for a war

Roman generals were always eager to find new areas to invade and conquer, as it brought them great glory and fame.


Caesar was no different, and he saw the region of Transalpine Gaul as an opportunity to make a name for himself.


So, while acting as consul in 59 BC, Caesar successfully had himself assigned the region of Cisalpine Gaul as governor.


Not only would this appointment keep himself safe from legal action following his abuse of power while consul, but it would also place him in a geographic location near Transalpine Gaul in order to prepare for a military invasion.


However, before launching his military campaign in Gaul, Caesar required a legitimate cause for invasion.


Thankfully for Caesar, a situation occurred in 61 BC that could be used as a pretense for war.


In that year, a group called the Helvetii from Switzerland were preparing to migrate to southern Gaul.


The Helvetians were a coalition of tribes who were displaced from their traditional homelands (either by military or environmental factors) and attempted to seek a new settlement in the south-west of Gaul.


However, to reach their destination, they had to pass through Roman territories. This could easily be seen as an act of war, or an attempted invasion.


Also, the Romans had an ally in the area of southern Gaul that the Helvetii would pass through, called the Aedui.


Both of these facts could easily justify a military operation by Caesar that would allow him to move into Transalpine Gaul.

The wars begin

The Helvetii were able to violate Gallic territory, ransacking Bibracte, the Aedui capital.


With Caesar's prompting, the Aedui officially asked for military support from Rome.


In response to this request, Caesar followed the Helvetii into southern Transalpine Gaul and defeated them at the Battle of Bibracte in March of 58 BC.


The Helvetti were defeated and left the area. Now, Caesar was in the region he wanted to conquer and looked for further reasons to continue his march into Gaul.


The leader of the Aedui, Diviciacus, told Caesar that a Germanic tribe, the Suebi, had also attacked them and had taken some of his citizens as hostages.


To further help his allies, Caesar marched his Roman legions north, into the centre of Gaul and defeated the Suebi at the Battle of Vosges on the 14th of September, 58 BC.


This had drawn Caesar into the centre of Gaul from where he could begin exploiting new situations which allowed him to expand his conquests.


Caesar was now determined to subdue the entire of Gaul.


As winter arrived at the end of 58 BC, Caesar built a winter camp for his soldiers to rest in and then traveled back to a city in Cisalpine Gaul to prepare for the next campaign season the next year. 


During this time, he began writing his own account of his wars in Gaul. This document survives and is known as the Gallic Wars. 


He wrote it to be read by his fellow citizen back in Rome so that he could boast about his successes, but it also served as a way to justify his invasion of Gaul in case he was accused of acting illegally.

Attacks against the Belgae and Nervii

As spring arrived at the start of 57 BC, Caesar returned to his army's camp in central Gaul. He was told that during the winter, tribes in the region of modern Belgium had created an alliance to defend against Roman aggression.


Caesar decided to take the initiative and launched an attack on the Belgian tribe called the Remi.


Facing defeat, the Remi surrendered to Caesar and formally became a Roman ally. This outraged the other members of the Belgian alliance and, when Caesar was away, attacked a Remian settlement.


When Caesar received news of the attack, he decided to defend his new allies. The attacking Belgians fled back to their own towns and following a siege by Caesar's troops, the tribes also surrendered.


However, one powerful Belgic tribe, known as the Nervii, refused to surrender and prepared to fight. Caesar, once more taking the initiative, marched his army into Nervii territory.


However, while building a camp, the Romans were caught off guard and were attacked. In the resulting Battle of the Sabis, the Romans were almost defeated.


According to Caesar's own account, it was due to superior Roman discipline and his own personal leadership that saved the day.


The battle turned to Rome's favour and turned into a slaughter of the Nervii. Of the 60,000 men that attacked his army, Caesar claims only 500 survived by the end of the battle.


The Nervii were defeated and surrendered to Caesar, as well as other Gallic tribes in the north-west of Gaul.


As winter arrived at the end of 57 BC, Caesar once more built a winter camp for his soldiers in Gaul, and he again travelled back to winter in Cisalpine Gaul to add new chapters to his written account of the war.


When Caesar sent his summary back to Rome to be read aloud to everyone, the Senate announce that 15 days of public thanksgiving were to be celebrated on Caesar's behalf: something which no other Roman had been honoured with before.

Naval war against the Veneti

When Caesar returned to his army in France at the beginning of 56 BC, his men told him that they had problems with a Gallic tribe called the Veneti, which had surrendered to Caesar the previous year.


During the winter, the Veneti were told that they had to supply food for Caesar's legions while they were at camp.


However, the Veneti quickly became resentful of the demand, had stopped sending the required food and, when Romans were sent to investigate the reason, they were captured and imprisoned by the Veneti.


As was to be expected, Caesar marched his army against the Veneti to force them to submit once more.


The Veneti were prepared for Caesar's attack. Since the they were located along the coast of north-western Gaul, the Veneti were a sea-going people and had a strong navy.


When Roman forces marched on their towns, the Veneti would simply abandon their towns, board their ships and sail further along the coast to safety.


Since Caesar did not have a fleet, he was not able to force the Veneti into a traditional battle.


After weeks and months with limited progress, Caesar ordered his men to build him a fleet and recruit sailors from other Gallic tribes who had allied themselves with him.

Once Caesar's fleet was ready, he launched a large naval attack on the Veneti ships. At the Battle of Morbihan, which probably occurred in late summer, hundreds of ships on both sides clashed.


While the Veneti were more skilled on the water, Caesar's troops used grappling hooks to tie down enemy vessels, allowing their soldiers to board and defeat them. Following the crushing defeat, the Veneti once more surrendered to Caesar.


The rest of 56 BC was spent conquering various Gallic tribes in the south-west of Gaul. Many settlements continued to resist Roman conquest, but one-by-one they were either defeated or surrenders. 


By the end of 56 BC, Roman forces wintered in northern Gaul, while Caesar returned to Cisalpine Gaul to rest and continue writing his Gallic Wars.


During this time, Caesar invited the other two members of the First Triumvirate, Crassus and Pompey, to visit him in the Cisalpine town of Lucca. The three men held a conference there where they agreed to continue their political alliance. 


As part of their agreement, Caesar was given a five-year extension to his military command in Gaul, and that Pompey and Crassus would stand for the consulships of 55 BC.

Crossing the Rhine

With the beginning of campaigning season in 55 BC, Caesar once more joined his troops in Gaul.


Caesar had received a request from Germanic tribes to his east to migrate into Gaul and settle there.


Caesar saw their proposed massed migration as a military threat and denied the request.


Despite Caesar's rejection, two Germanic tribes, the Usipetes and the Tencteri, decided to move into Gaul anyway by crossing the Rhine River, which separated the two territories.


Angered by their willingness to ignore his order, Caesar marched his troops west and attacked the tribes.


The majority of the tribespeople were not soldiers but included many women and children.


Regardless, Caesar wanted to make an example of them and claims to have slaughtered over 400,000 people.


With these people crushed, he wanted to send a warning to other Germanic tribes so that they didn't try to attempt further migrations into Gaul.


Caesar ordered his military engineers to construct a 230-metre wooden bridge across the Rhine.


Once build, Caesar's army marched across it, and attacked a series of local villages, burning them down.


Once Caesar believed that his message was clearly received by the surrounding tribes, he marched his men back over the river and burnt the bridge down.

First invasion of Britain

In August of that year (55 BC), Caesar marched his troops to the northern coast of Gaul where he ordered his men to board the ships of the Roman fleet that had been built in the previous year.


These men were sailed across the English Channel and landed on the coast of Britain. This was the first time any Roman had reached this distant island.


The local British tribes knew Caesar was coming and had called their warriors to prepare for any attack.


However, when the Roman legions stepped onto British soil, the local warriors retreated inland and only engaged in limited fighting.


As 55 BC was drawing to a close, Caesar did not want to winter in Britain and ordered his men back onto the ships.


The Romans returned to Gaul where they spent the winter. Once more, Caesar returned to Cisalpine Gaul to continue his writing.


Many modern historians believe that the crossing of the Rhine and the landing in Britain were intended as publicity stunts by Caesar.


Neither event resulting in significant conquests for Caesar, but they did sound impressive.


Many believe that Caesar wanted to have something dramatic to write in his account of the wars for that year so that the people in Rome wouldn't forget about him while he was away.

Return to Britain

In 54 BC, most of Gaul was under control and Caesar decided to make a more focused effort to invade Britain.


After new ships were built, he took 5 legions and 2000 cavalry across the English Channel. This time, there was no resistance as the Roman troops landed in Britain.


Caesar moved inland to seek battle with local tribes. However, the Britons preferred to use guerilla attacks and avoided battle. 


In response to the Roman threat, the tribes united under a leader called Cassivellaunus, who was the chief of the Catuvellauni tribe.


The two sides clashed in small skirmishes and the Britons were defeated on a number of occasions. Caesar then capitalised on disunity between the tribes, and some began allying with him. 


The Roman troops advanced on Cassivellaunus town, at which point he surrendered to Caesar. Resistance seems to have ceased at this point, even though Caesar hadn't captured much territory.


Satisfied with his gains in south-eastern Britain, Caesar returned with his troops to spend the winter in Gaul. However, things were not well upon his return.


The harvest during 54 BC had been poor in the Gallic territories, and once more, the Gauls were tasked with feeding the Roman troops during winter. As had happened before, the local tribes became resentful. 


To minimise the discontent and to limit the amount of food taken from any one region, Caesar spread his legions out across Gaul during the winter.


However, this isolated each Roman army from each other, which made it an ideal time for a revolt.

Ambiorix's revolt

Over the winter of 54/3 BC, several Gallic tribes rose up and attacked the scattered Roman camps. This revolt was led by Ambiorix, the chief of the Eburones tribe.


One Roman army was convinced to abandon their camp and march for help, only to be surrounded and annihilated by the Gauls. Another Roman army was besieged and cut off from communication with potential reinforcements.


The speed of the uprising and the early victories by the Gauls alarmed Caesar and he decided that if he didn't act quickly, all of Gaul would be lost. He quickly marched his army out and saved the Roman army under siege.


As spring arrived, Caesar spent the rest of the 53 BC marching across Gaul, punishing the various tribes who had risen up against him.


Caesar's punishments were brutal. He not only defeated the men in battle, but also attacked women and children in towns across the country and destroyed many settlements. 


By the end of the year, most of the tribes had surrendered again to Caesar, but resentment at Caesar's tactics remained.


Many Gauls realised that if there was a coordinated attack against the Romans, they might still stand a chance of victory against Caesar.


Over the winter of 53/2 BC, the Romans were uneasy, as news of a more dangerous revolt was building.

Vercingetorix's revolt

In 52 BC, almost all of Gaul rose up in defiance against Caesar. The many Gallic tribes we led by a chief called Vercingetorix.


Vercingetorix had been an allied commander and had fought alongside the Romans on many occasions. He used his knowledge of Caesar's strategies and tactics to devise a plan that he thought would finally drive the Romans from Gaul.


Vercingetorix ordered his troops to isolate the Roman army from both reinforcements and supplies. The Gauls destroyed their own farmlands and any towns that could be used by their enemies.


Any food and supplies that the Gauls needed were stored in a number of important and defensible cities, such as Alesia.


The idea was that the Romans were forced to attack these towns and, when they did, the Gauls would use overwhelming numbers to attack the Romans.


With the entire region in revolt and his troops cut off from help, Caesar had to act quickly even before winter had ended.


Doing exactly what Vercingetorix thought, Caesar attacked one of the storage cities, Avaricum, and captured it. 


Vercingetorix then retreated to Gergovia where he successfully repelled Caesar's attack. This victory encouraged the rebels.


Vercingetorix then moved on to the storage city of Alesia, but Caesar moved quickly and besieged the city.


The following Battle of Alesia is one of the most famous battles in all of the Gallic Wars. 


The city of Alesia was naturally protected by two rivers and nearby mountains. Vercingetorix believed he could hold out in the city for long enough for other Gallic armies to come to his aid.

To his surprise, Caesar build an entire defensive wall around the city (17 kilometres long and 3.6 metres high) to stop supplies getting in.


Then, Caesar built another wall, up to 21 kilometres long, around the original wall as a way of defending against any Gallic armies that might come to save Alesia.  Vercingetorix was trapped and was running out of food.


Another Gallic army did arrive to help, and they attacked the outer Roman wall while Vercingetorix's forces attacked the inner Roman wall.


They hoped that the simultaneous attacks would overwhelm Caesar's men. However, through discipline and inspiring leadership from Caesar, the Romans were able to defeat both forces and the Gauls were eventually forced to surrender. Vercingetorix himself was sent back to Rome as a prisoner.


The battle was a turning point in the war, as it resulted in a decisive victory for Caesar and his legions.


After this battle, the Gauls were no longer able to mount any serious resistance to Rome.


Caesar spent the years of 51 and 50 BC crushing minor pockets of resistance around the region.

The Gallic Wars come to an end

By 51 BC, all of Gaul had been conquered by Rome and the Gallic Wars came to an end. This was a major victory for Julius Caesar and the Roman Republic.


The Gallic Wars had lasted for nearly a decade, involved around 300 separate battles, with the capture of over 800 settlements by Rome.


The Gauls themselves paid the highest price of the conquest. The various Gallic tribes had now suffered numerous conquests, defeats and slaughters at the hands of Caesar's troops.


Of an estimated 6,000,000 people that had been living in Gaul before Caesar arrived in 58 BC, around 1,000,000 had been killed, and another 1,000,000 had been sold into slavery by 50 BC. 


However, the war was a turning point in Roman history. It established Rome as a major power in the world and paved the way for the Roman Empire.


The Gallic Wars also cemented Julius Caesar's reputation as one of the greatest military commanders in history.

In the long-term, the Gallic Wars also had a profound impact on Rome and its empire.


First, the wars increased Rome's territory significantly. Second, the defeat of the Gauls established Rome's dominance over them once and for all.


Finally, the war made Julius Caesar one of the most famous men in Roman history and laid the foundation for his future political career. 

Further reading