Battle of Alesia


Caesar arrived in Gaul in 58 BC. At that time it was the custom in Rome for the highest elected official, the consul, to be designated senior consul at the end of his term of office and to be appointed by the Senate as governor of the provinces. Caesar was consul in 59 BC, and at the end of his term of office he prompted the Senate to appoint him prefect of Sannan Gaul. Although a senior consul’s term of office was normally only one year, Caesar was able to use the power of the former three-headed alliance to secure an unprecedented ten-year term. He was given a senior rulership, with absolute supremacy in his province.

One by one, Caesar defeated the Gaulish tribes of the Helvetii, the Bilicis and the Nervi, and forged an alliance with many others. The step-by-step victories in the Gallic wars earned the Roman Republic much wealth: spoils of war and taxable territory. Caesar himself made a great deal of money as army commander by selling prisoners of war. But his victories and fame also brought him enemies. In 54 BC Caesar’s alliance with [Gnaeus Pompey and Crassus ended after the death of Caesar’s daughter and Pompey’s wife Julia and after Crassus was killed at the Battle of Calais. As Caesar lost his political alliance with Pompey, the champions of the Republic such as Cato the Younger became hostile to Caesar, suspecting and accusing him of wanting to overthrow the Republic and become King of Rome.

In the winter of 54-53 BC the Eburones, led by Ambioric, who had already submitted to Rome, rose up against the Romans and used a carefully laid ambush to destroy the XIVth legion. This was a huge blow to Caesar’s Gallic policy, as he lost a quarter of his army and the political situation in Rome itself prevented him from receiving support. The revolt of Ambioric was the first clear Roman defeat in Gaul (but as the army was stationed outside, the blow did not damage Caesar’s military prestige). It inspired national sentiment and other revolts in Gaul. It took Caesar almost a year to regain control of the situation and to reassure the tribes. But the revolts in Gaul did not end there. The Gaulish tribes realised that they could only gain independence if they were united. At the suggestion of the Edouvians, Caesar’s original allies, the Gauls met at Biblakte. Only the Remi and the Lingones decided to maintain their alliance with Rome. The assembly elected the Avernian Wesengetorix as commander of the Gaulish allies.

Caesar himself was in southern Gaul at the time and he was unaware of the formation of this alliance against him. The earliest sign of the revolt against Rome was when the Carnotes killed all the Romans in Cenabum (modern Orleans). This was followed by the killing of Roman citizens, merchants and immigrants in other important Gallic cities. On receiving this news, Caesar immediately reorganised his troops and marched across the still snowy Alps into central Gaul. Caesar moved quickly, surprising the Gallic tribes. He divided his forces, sending Titus Rabinus with four regiments north to conquer the Senon and Parisii. He himself took six regiments and the cavalry of the Germanic allies in pursuit of Wesengetorix. The two armies met at Germovia, where Wessengetorix’s army was stationed in an impregnable fortress, and Caesar had to withdraw to avoid a major defeat after suffering heavy losses of 700 killed and 6,000 wounded. Fearing a return of the Caesars, Wercenetorix turned to the defensive in the summer of 52, but was unexpectedly defeated and lost his cavalry advantage, and Caesar’s further counter-attacks left the Gauls in danger of being scattered. Realising that it would be difficult to defeat the Roman army in a regular field battle, Wessengetorix decided to reorganise his army at Alesia.

The siege and the battle

Assuming that Alesia was located in Ariz St. Lena, the map of the siege built by Caesar when he surrounded Alesia shows the location in present-day France. The circles on the map show the weaknesses of the wall to the north-west

Alesia was a fortress built on a hill, surrounded by a river valley and very well defended. As there was no prospect of victory in a strong attack, Caesar decided to surround Alesia and force the opponent to surrender after running out of food. With an estimated 80,000 soldiers in Alesia, plus the local population, the siege would not take long. To ensure that the fortress was completely cut off from external supplies, Caesar ordered a wall to be built around the fortress. The construction of the wall is described in detail in Caesar’s “The Gallic Wars”. Within three weeks his engineers and soldiers had built a wall 18 kilometres long and four metres high. Inside the wall (both on the side of the super-enclosed fortress) there was also a ditch four and a half metres wide and about one and a half metres deep. The ditch closest to the fortress was filled with water from the surrounding river. A full set of traps was also set in front of the ditch and Roman archers were placed on the watchtowers on the perimeter wall.

Wessengetorix’s cavalry frequently attacked the site to prevent a complete siege, but Caesar’s Teutonic auxiliary cavalry was able to fend off the attacks. About two weeks after the work on the wall began a group of Gaulish cavalry was able to break out of the unfinished section. Knowing that the intention of this cavalry breakout was to ask for support from all of Gaul, Caesar ordered an outer wall to be built outside the inner wall, giving his troops an average space of 120 metres between the two walls. The outer wall, which was identical in design to the inner wall, was 21 kilometres long and also included four cavalry battalions. The Roman besieging army prepares itself for being surrounded.

At this point the situation inside Alesia continued to deteriorate. 80,000 soldiers plus the local population and the city’s food reserves were low. Wessengetorix decided to expel the women and children from the city to save food, and in addition he hoped that Caesar would open a section of the wall to let the civilians out and he would have the opportunity to break the Roman siege. But Caesar ordered that the civilians, women and children should not be let out of the wall, so they were left in a desperate situation in no-man’s land between the inner wall and the city walls. These people were relatives of the soldiers inside the city and their condition greatly demoralised the city’s defenders. Although Wesengetorix kept boosting the morale of his soldiers, he was in danger of having his own men surrender. It was at this point of impending despair that reinforcements arrived, giving the soldiers within the city new hope.

At the end of September the Gauls under the command of Comius attacked Caesar’s outer wall, while Wesengetorix ordered an attack on the inner wall, but both attacks were repulsed at sunset. The following day the Gauls attacked by night. They penetrated several sections of Caesar’s wall, but the cavalry led by Mark Antony and Gaius Tertius reacted quickly to repel the Gauls. Meanwhile Wessengetorix ordered an attack on the inner wall, but as his men had to fill the ditch first his attack could not be carried out at the same time as the attack on the outer wall, and the Romans were prepared this time. But the situation of the Roman soldiers was also quite bad at this time. They themselves were surrounded, out of food, already rationed, and almost all of them exhausted.

The following day, 2 October, Vercassivellaunos, a cousin of Vercenegetorix, led a general attack of 60,000 men, who particularly targeted the weak point of the siege. Caesar tried to hide this weakness, but it was discovered by the Gauls. The natural conditions of the place made it impossible to build a complete wall. In the meantime, the men of Wesengetorix were attacking the inner wall from all directions. Caesar, trusting in the discipline and courage of his men, ordered that there should be no retreat. He himself was constantly encouraging his soldiers at the front. Rabinus’ cavalry reinforced the wall where it had been breached. But the situation of the Romans was becoming more and more urgent. Caesar therefore decided to repel Wesengetorix’s men by launching a counter-attack against those attacking the inner wall. Just as the defences of Labienus were about to collapse Caesar decided to take desperate measures and he led thirteen cavalry units (about six thousand men) to attack the reinforcements of sixty thousand men from the rear. This action took the attackers and the defenders by surprise. The men of Labienus saw their commander take the lead and risk a charge and immediately their morale was boosted, while the Gauls retreated in haste and Vercasivir the Elder was taken prisoner. In ancient warfare a camp collapse was immediately and instantly unstoppable, and the Gaulish allies began a general rout, falling victim to the Roman pursuers. Caesar himself said in his Gallic Wars that it was only because his soldiers were exhausted that the Gauls were not all destroyed.

Recognising that his reinforcements had been repulsed, Wesengetorix decided to surrender. After a final speech to the garrison, he rode into the Roman camp alone the next day and surrendered his arms to Caesar, ending the Battle of Alesia.

The aftermath

Alesia was the first and last major and organised resistance to a Roman invasion in Gaul. Thereafter Gaul was conquered by Rome and became a Roman province, which in turn was subdivided into smaller administrative regions. It was not until the 3rd century that the independence movement re-emerged here. The defenders of Alesia and the survivors of their reinforcements were taken prisoner. They were sold into slavery or given to Caesar’s soldiers as spoils of war, but the captives of two tribes, the Eduvians and the Avilni, were pardoned and released to ensure the loyalty of these two important tribes to Rome.

For Caesar Alesia was a major military and political victory. Even the Senate, run by Cato and Pompey, who opposed him, had to celebrate it for 20 days, but they still refused to allow Caesar the honour of a triumph – the highest honour for a Roman warrior. Political hostility between the two sides continued to rise. Two years later, in 50 BC, Caesar crossed the Rubicon and began the Roman civil war that had lasted from 49 to 45 BC. He won the civil war, was elected consul every year during it, was appointed provisional dictator several times thereafter, and was finally made dictator for life by the Senate in 44 BC. His growth in power and honour increasingly conflicted with the foundations and traditions of the Roman Republic, a process which eventually led to its demise and the beginning of the Roman Empire.

The fate of Caesar’s cavalry generals varied. Rabinus, who supported the faction of the nobles representing the interests of the conservative aristocracy in the civil war, was killed at the Battle of Munda in 45 BC. Trebonius, one of Caesar’s most trusted lieutenants, was named consul by Caesar in 45 BC, and was one of the senators who plotted to assassinate Caesar on 5 March 44 BC. He was himself murdered a year later. Antony always followed Caesar, and he became his knight commander, second in command. He guarded Italy for Caesar during the civil war. In the first 44 years he was chosen to be Caesar’s co-consul. After Caesar’s assassination he persecuted Caesar’s assassins and reached the height of his power by forming the latter three-headed alliance with Octavian and Lepidus. He was defeated by Octavian at the Battle of Cape Axion in 31 BC and fled to Egypt with his lover and ally Cleopatra VII, both of whom committed suicide the following year.

Wesengetorix was captured and spent the next five years in prison waiting for Caesar to celebrate his triumph. The enemy leader was traditionally dragged and displayed in a triumphal procession, and at the end of the procession was pressed into the underground prison of Mamertini to be hanged. But he has become a national hero and a symbol of the spirit of freedom in modern France.

Historical controversy

The location of the Battle of Alesia has been disputed for many years. Two cities are the most likely: one is Alaise in Franche-Comté and the other is Alize-Saint-Lena in the department of Cordor. The latter was supported by Napoleon III, who paid for archaeological excavations in the 1860s which produced artefacts that seemed to indicate that there had been a Roman barracks in the area. He built a statue of Wesengetorix on the historic site he found.

Despite this debate, there are always those who doubt that Ariz San Lena was indeed the site of the battle. Some say, for example, that the topography of the area does not fit Caesar’s depiction. Moreover the place was too small to accommodate 80,000 Gaulish infantry, with the addition of cavalry and other men.

Another theory is that the battle broke out at Chaux-des-Crotenay on the Jura Pass, and preliminary research in the area has revealed a complex Roman fortress that matches Caesar’s description. But further research is needed to prove that this was indeed the site of the Battle of Alesia.

In an episode of The Adventures of Asterix the author deals humorously with the uncertainty of the location of the Battle of Alesia. Asterius and Obelix together encounter relatives who fought in the battle and who are willing to talk about the victory of Wesengetorix at the Battle of Germovia, but refuse to say anything about the Battle of Alesia and say that no one knows where it took place.

Specific figures on the strength and casualty figures on both sides of the battle are also unclear. As these figures are very powerful propaganda tools, they were always to be doubted. Caesar’s claim in his Gallic Wars that Gaul’s reinforcements numbered 250,000 may have been an exaggeration to inflate his victory. Unfortunately the only records of the time were written by the Romans, so none of these figures may be accurate. Modern historians generally estimate their numbers to be between 80,000 and 100,000. The only plausible fact is that each of Caesar’s legions received one Gaulish prisoner as a slave, which suggests that at least 40,000 people were captured, most of them inside the besieged fortress (in addition, if the number of Edouvian and Avernian prisoners of war released by Caesar afterwards is to be believed, the number of captives must have increased by at least another 20,000 or so). The reinforcements may have suffered great losses. Generally armies that were pursued by Roman cavalry after losing their formation and being routed suffered great losses.

Aerial photograph of the old battlefield at Alesia

1 thought on “Battle of Alesia”

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