Caesar Defeats the Gauls

52 BC

After ten years, Julius Caesar finally managed trap the Gallic leader Vercingetorix in a hill fort and surrounded him. He then fought off a second Gallic army that had come to break the siege.

In the winter of 53–52 BC the Carnutes rebelled in Gaul, a region that had recently been annexed by Julius Caesar and his legions. The Carnutes were a Celtic tribe who gave their name to Chartres, which had been their Druidic headquarters. In their oppidum (fortified town) of Cenabum (now Orléans) they rose up and massacred all the Roman citizen traders, together with Caesar’s supply officer. To the Senone people in the northeast this was a signal to form guerrilla forces and begin disrupting the Roman army’s food supply.

Elsewhere other Gallic forces moved against the Roman legions in their winter quarters. At the time, Caesar was performing his magisterial duties in Cisalpine Gaul (now northern Italy). However, in late February he hurried across the Alps, defying heavy snows in the Cevennes mountains, to arrive unexpectedly at Agedincum (now Sens in Burgundy) where he mustered his legions. Titus Labienus was sent with four legions to suppress the Senones and the Parisii to the north, while Caesar himself led six legions towards Gergovia, the hilltop stronghold of the Arverni near what is now Clermont-Ferrand.

The Arverni’s leader, Vercingetorix, was not just a formidable fighter. He was also a skilled politician and had secured the support of the Aedui tribe, Caesar’s former allies, who had served for years as auxiliaries and were highly valued by Caesar as cavalry. While Caesar was besieging Gergovia, the Aedui rebelled and massacred some of the Roman troops and all of the Roman citizens in Cabillonum, now Chalon-sur-Saône, to his rear. With his siege of Gergovia now placed in peril, Caesar attempted to take the hill fort by storm but was repulsed, at the cost of heavy losses. Vercingetorix had brought about Caesar’s first outright defeat in Gaul, forcing him to withdraw.

Tribal leaders who had been loyal to Caesar switched their allegiance to Vercingetorix, who was elected commander-in-chief: some sources say he was named King of Gaul. It is thought that as many as forty-five tribes joined in the struggle against Rome. They set fire to the army depot at Noviodunum (now Nevers) and massacred the Roman merchants there.

The situation Caesar now found himself in was critical. His tribal allies had deserted him. The Arverni, elated by their victory at Gergovia, were at his rear; the Bituriges, from modern Bordeaux, were on his left flank; and the Aedui barred his front. According to the military theoretician J. F. C. Fuller, one of the pioneers of modern tank warfare: ‘One thing alone saved him – his own invincibility.’

With his supply lines under attack Caesar fell back towards the Loire, where he was reunited with the legions of Labienus. He also replenished his cavalry with German auxiliaries. The Aedui, particularly, viewed their replacements with horror, considering them to be brutal barbarians. Vercingetorix was now in command of superior numbers, but Caesar managed to hold him off with his German horsemen.

That summer, Vercingetorix found it difficult to maintain his leadership without a clear victory. The tribes under his control were accustomed to warring with each other for territory and plunder; they found co-operation difficult at the best of times. However, Vercingetorix managed to persuade the tribal leaders to destroy their grain stores so that the Romans would be deprived of food during their campaign. The Bituriges burnt more than twenty of their own towns in one day but begged that Avaricum (now Bourges) be spared. It was, as Caesar said, ‘the fairest city in the whole of Gaul’ and they thought it could easily be defended. Caesar took it by storm within a month.

Vercingetorix was now on the defensive and he withdrew his huge army to the hillfort of Alesia, the capital of the Mandubrii. This oppidum was on the summit of Mont Auxois, just above the present-day village of Alise-Sainte-Reine, some thirty miles northwest of Dijon.

Caesar immediately grasped the changed situation, so he isolated Vercingetorix from his allies by surrounding Alesia. The key to Caesar’s strategy was his army’s engineering ability. The entire plateau of Alesia was quickly encircled by a series of walls, ten miles long in total. His men dug a ditch that was eighteen feet wide, at the side of which was a trench filled with water. ‘Mantraps’ were dug. A mantrap was a carefully concealed hole in the ground, several feet deep, with a sharpened spike in its centre. Anyone falling into the hole could well be impaled. Then a second wall, nine feet high and capped with breastworks, was built far behind the first line of defence. There were square towers at regular intervals where the awesome siege equipment of the Romans was mounted. This was all designed to keep Vercingetorix and his army trapped inside.

But Caesar also expected other Gauls to rally to the cause of Vercingetorix. So he began constructing an entire second line of fortifications which was parallel to the first and faced outwards. These defences were between thirteen and fifteen miles long. Caesar’s army was now safe between the two rings of fortifications and the Gauls could scarcely believe their eyes when they saw the scale of this feat of military engineering.

Vercingetorix sent out cavalry detachments to harry the building work and the foraging parties while the construction was underway. As the siege tightened, there were cavalry battles in the three-miles-wide corridor between the outer wall of the hill-fort and the inner wall of Caesar’s circumvallation. On the night before the Roman fortifications completely encircled Alesia, Vercingetorix sent out all his cavalry. Their mission was to return to their own tribes and conscript all the men of military age. The lives of 80,000 men inside the fort were in their hands. The horsemen escaped through the last gap in the Roman lines and galloped off to raise reinforcements.

After calculating that there was barely enough corn to hold out for a month, Vercingetorix introduced strict rationing. As stocks ran low all the townspeople who could not bear arms were marched from the hill fortress and into no-man’s-land. The women and children and the aged cried out pitifully as they begged the Romans to take them as slaves, but that would have given the Romans the problem of feeding them. Caesar posted guards to ensure that his troops would refuse the women and children admission and they were left to starve between the lines.

Meanwhile, the other tribal chieftains arrived with what Caesar said was a quarter of a million men. Modern scholars believe that the warriors amounted to somewhere between 80,000 and 100,000. A great cheer went up inside Alesia at the sight of them. Vercingetorix and his men thought they had been saved.

As these fresh troops encamped on a hill that was a mile outside the Roman outer wall, Caesar and his lieutenants, including Gaius Trebonius and Mark Antony, braced themselves for a battle on two fronts.

The fighting began with a cavalry battle on the first day, which ended with a Roman victory thanks to the daring of the German horsemen. After a day’s rest the Roman fortifications were simultaneously attacked from the inside and the outside, but they held firm.

According to Julius Caesar’s Commentary on the Gallic Wars:

As long as the Gauls were at a distance from the entrenchments, the rain of javelins which they discharged gained them some advantage. But when they came nearer they suddenly found themselves pierced by the goads or tumbled into the pits and impaled themselves, while others were killed by heavy siege spears discharged from the rampart and towers. Their losses were everywhere heavy and when dawn came they had failed to penetrate the defences at any point…

The besieged lost much time in bringing out the implements that Vercingetorix had prepared for the sortie and in filling up the first stretches of trench, and before they reached the main fortifications heard of the retreat of the relief force, so they returned into the town without effecting anything.

At around midday on the fourth day the Gauls attacked again from both sides. After a terrible battle, the Romans won a great victory. As Caesar charged the relief force from the front the German cavalry hit them in the rear and they were scattered. Completely routed, they were pursued from the field by the German auxiliaries.

On the following day, with no hope of relief, Vercingetorix surrendered. He gathered the tribal leaders and told them that he had not made war for personal reasons but for the freedom of Gaul. Now they must decide whether to kill him in order to appease the Romans or hand him over alive. A deputation was sent to Caesar, who ordered the defeated Gauls to lay down their arms and bring their tribal chiefs to him. Then he sat on the fortification in front of his camp and waited.

Vercingetorix’s surrender to Caesar is recorded by Plutarch:

Vercingetorix, after putting on his most beautiful armour and decorating his horse, rode out through the gates. Caesar was sitting down and Vercingetorix, after riding round him in a circle, leaped down from his horse, stripped off his armour, and sat at Caesar’s feet silent and motionless, until he was taken away under arrest to be kept in custody for the triumph.

J.F.C. Fuller wrote:

Thus this remarkable siege was brought to an end by the simultaneous defeat of two armies by a single army, no greater than the one and incomparably smaller than the other. An army which not only was the besieger but itself was besieged, and which had to hold twenty-five miles of entrenchments in order, at one and the same time, to achieve its aim and secure itself against defeat. In spite of the paucity and frequent vagueness of details provided by Caesar, and the consequent difficulty in reconstructing some of the incidents, the siege of Alesia remains one of the most extraordinary operations recorded in military history.

Some 20,000 Aedui and Arverni were separated from the prisoners and returned to their tribes in an attempt to regain their loyalty. The Arverni also had to hand over some hostages in order to ensure their future good behaviour. The other survivors were divided among Caesar’s soldiers and sold as slaves.

In Rome the Senate honoured Caesar with a twenty-day thanksgiving. Vercingetorix was taken to Rome in chains where he remained as an honoured prisoner for the next six years while Caesar fought Pompey in the Civil War. Once Caesar was in sole control of the Roman world, he had Vercingetorix exhibited in his Gallic triumph in 52 BC. Then, according to custom, the Gaul was strangled in the depths of the Mamartine Prison in Rome.

The defeat of Vercingetorix at Alesia essentially ended any hope of an independent Gaul. Caesar had two more years of mopping up before he had completed the pacification of the province and the Romanization of Gaul remains one of his most enduring achievements.

The ruins of the Alesia fortifications were rediscovered some nineteen centuries later. Mindful of the contribution of German cavalry to the defeat of Vercingetorix, Emperor Napoleon III of France arranged for a massive statue of the Gallic leader to be erected on the site. Vercingetorix had come to symbolize the courage of France in fighting her enemies. Soon after that, Napoleon III fell from power having also been defeated by the Germans, this time at the Battle of Sedan in 1870.

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