The Gallic War, Book I

58BC: The Repulsion of the Helvetii & Expulsion of Ariovistus from Gaul

Gaul comprised three areas inhabited by the Belgae, Aquitani and Celts/Gauls, all of whom had their own language, customs and laws. Their geographical location is described. Of the Celts, the Helvetii, who lived in modern Switzerland, were thought to be the bravest because of their proximity to the Germans.

A map of Gaul in the 1st century BC, showing the relative positions of the Helvetii and the Sequani. (c) US Military Academy, Dept. of History.

In 61 BC, Orgetorix, the richest and highest ranking of the Helvetii, conspired to seize sovereignty and persuaded his people to emigrate in order to extend their territory as they were hemmed in by the natural barriers of a river, a lake and mountains. He also persuaded Casticus, a Sequanian, and Dumnorix, an Aeduan, to swear an oath of loyalty to him and, in return, he would help them to seize the throne in their tribes. Orgetorix was betrayed; he escaped trial and condemnation but died, probably by his own hand. However, the Helvetii decided to go ahead with the migration: they burned all their towns and villages, together with their grain, except for what they could take with them, and persuaded some of their neighbours to do the same. Of the two routes available by which to leave, they chose the one across the Rhone through the Roman province of Transalpine Gaul as they thought the Allobroges tribe would be friendly or easily conquered.

They set out on 28th March 58 BC. When Caesar heard, he travelled from Rome to Geneva, the frontier town of the Allobroges, had the connecting bridge destroyed and ordered troops to be raised in the province. When the Helvetii sent an embassy to Caesar to say they intended no trouble but merely requested a route through the province, he did not trust them, remembering a previous attack by the Helvetii on L. Cassius, a Roman consul, and his army in 107 BC; however, using delaying tactics to give him time to gather an army, Caesar told the embassy to return on 13th April. In the meantime he fortified the bank of the Rhone between Lake Geneva and the Jura mountains, the frontier between the Helvetii and the Sequani, with a 16 foot high rampart, guarded at regular intervals. When the embassy returned, Caesar refused them passage through the province. Attempts to break through the Roman barricade were thwarted. The Helvetii were therefore forced to look to the other route through the territory of the Sequani, a narrow pass between the Jura mountains and the Rhone, difficult to pass through if attacked and therefore requiring the Sequani’s permission.

Dumnorix, of the Aeduan tribe, previously allied with Orgotorix and ambitious for power, gained this permission for the Helvetii, arranging an exchange of hostages. When Caesar heard about this and that the Helvetii intended to settle close to the province, he summoned a further five legions and quickly marched to the territory of the Segusiavi, just beyond the frontier of the province, repelling attacks by some local tribes. When the Ardui, Ambarri and Allobroges all told Caesar their lands had been plundered by the Helvetii and asked for his help, he knew he must act quickly to stop the Helvetii threat and protect these tribes who had previously been loyal to Rome. Upon learning that the Helvetii had managed, via rafts and small boats, to convey three quarters of their people across the Saone, a tributary river into the Rhone, Caesar attacked and killed a large number of the remaining quarter who had not yet crossed, thereby also avenging the Roman defeat fifty years earlier: these troops belonged to the Tigurini, one of four clans of the Helvetii, whose ancestors were responsible for sending the Roman army under the yoke and killing Caesar’s father-in-law in that battle.

Caesar then built a bridge across the River Saone and led his army across, intending to attack the remaining Helvetii. They sent an embassy to him, led by Divico who had commanded Helvetii troops in their previous victory against the Romans, saying that, if the Romans made peace with them, they would settle wherever Caesar wished; otherwise, Caesar should not rely on a victory where he had made a surprise attack on a small section of the Helvetii but should remember the Romans’ previous defeat which could well happen again. Caesar’s response was for the Helvetii to recompense the Aedui and Allobroges and provide hostages as a guarantee of peace. The Helvetii refused and continued on their journey the next day, closely followed by four thousand Roman cavalry. These cavalry suffered some casualties when they got too close but Caesar chose not to attack, deciding to keep a distance of five or six miles between them but preventing the Helvetii from looting.

Julius Caesar and Divico parley after the battle at the Saône. Historic painting of the 19th century inspired by a scene described by Caesar by Karl Jauslin.

After the Aedui continually postponed providing Caesar with the grain they had promised and which he desperately needed as he pursued the Helvetii, he summoned and reprimanded their chiefs. Liscus, their chief magistrate, told Caesar there were certain Aedui persuading the people not to hand over the grain because they believed that, once the Romans had defeated the Helvetii, they would overpower the rest of Gaul including the Aedui. In private Liscus confirmed Dumnorix was behind this, as Caesar suspected, a very ambitious man who had built up his personal wealth and power through intimidation, bribery and arranged family marriages with other tribes; he believed the arrival of the Romans had decreased his power whereas Roman defeat would increase his chances of securing sovereignty in his tribe and he had also been largely responsible for the recent cavalry losses.

In addition, as Dumnorix had secured a passage for the Helvetii through Sequani territory and an exchange of hostages without the knowledge and permission of either Caesar or the Aedui government, Caesar sent for Dumnorix’s brother, Diviciacus, a fair man who supported Roman interests, told him what he had learned about Dumnorix and requested that judgement should be passed on him either by Divicacus or the Aeduan state. Saying that he knew the allegations against his brother were true, Diviciacus begged Caesar for leniency to which Caesar agreed because of his regard for Diviciacus. Dumnorix was summoned, informed of the charges against him, warned against further action against Rome and placed under surveillance.

When it was reported that the Helvetii had camped at the bottom of a hill eight miles from Caesar’s camp, he ordered Labienus, his second in command, to climb to the summit with two legions while he himself with the rest of his forces marched along the same route taken by the Helvetii, the plan being to attack the Helvetii from all sides. However, Considius, in charge of a patrol sent ahead, wrongly reported that the Helvidii had control of the hill and so Caesar withdrew to a nearby hill. When he subsequently learned this was not so and that the Helvetii had moved camp, he followed them and pitched camp three miles away. Caesar decided to change route towards the town of Bibracte to obtain food supplies.

His plans were relayed to the Helvetii by some runaway slaves and, believing the Romans were retreating through fear, they followed Caesar and harassed his rear columns. In response Caesar sent his cavalry against them, while he took up position on a nearby hill, placing veteran and auxiliary troops on the hillside in such a way to give the impression it was totally occupied with troops, and building defences round their baggage. The Helvetii repelled the Roman cavalry, formed a phalanx and climbed the hill to attack the Romans but eventually retreated to a nearby hill as they could not withstand the impact of the Romans’ spears. As the Romans pursued, they were surrounded by fifteen thousand Boii and Tulingi protecting the Helvetian rear and the Helvetii again attacked.

Fierce and prolonged fighting continued until late into the evening with many casualties on both sides, but finally the Romans prevailed and captured Orgetorix’s daughter and one of his sons. The Helvetii who survived, around 130,000, withdrew to the territory of the Lingones to whom Caesar wrote, warning them against harbouring or helping the Helvetii. The Helvetii surrendered, giving hostages, surrendering their weapons and the slaves who had deserted to them. Six thousand of the Verbigeni fled to the German frontier but, on the instruction of Caesar, they were returned by the tribesmen through whose land they passed, and executed. The Helvetii and tribes who had helped them were ordered to return to their own country and to rebuild what they had burned as Caesar did not want the Germans taking over their land in close proximity to the Roman province. The Boii settled with the Aedui, at their request because of their bravery, and were later granted equal status. A census sheet was found in the Helvetii camp listing 368,000 tribesmen at the start of their campaign but only 110,000 returned home.

The Battle of Bibracte, 58 BC. (c) Cristiano64

The leading men of almost all the tribes in Gaul congratulated Caesar on his victory over the Helvetii as the latter’s intention had clearly been to become masters of Gaul. They also asked Caesar for a date for a pan- Gallic assembly, which led to Caesar’s second campaign that summer: Some Aedui chieftains met with Caesar privately afterwards to complain about German settlers, and in particular their king, Ariovistus, who had settled in Gallic territory at the invitation of the Sequani, fifteen thousand mercenaries initially, but up to one hundred and twenty thousand later, as they liked the good quality of land and standard of living. When the Aedui opposed them they had been forced to swear an oath of no further opposition and to hand over their children as hostages.

Their spokesman, Diviciacus, was the only one to have refused. In addition, the Germans had seized a third of Sequani land and were threatening to seize another third to house twenty four thousand of the Harudes tribe who had joined them; he feared that the Germans would soon occupy the whole of Gaul. Fearing Ariovistus’ cruelty towards the hostages and the Sequani in particular, and his quest to rule the whole of Gaul, Diviciacus begged for Caesar’s help as he was the only deterrent to the Germans or the Aedui would be forced to seek a place to live outside Gaul. Caesar knew he must act against the Germans’ aggression as doing nothing could result in them entering the province and then marching on Italy.

After Ariovistus refused Caesar’s first invitation to meet, Caesar sent him an ultimatum: not to bring any more Germans into Gaul, to return all Aeduan hostages and not to make war on the Aedui or their allies; otherwise, he would be punished. Ariovistus replied that the Romans should not interfere with how he ruled, would not return the hostages but would refrain from attacking the Aedui and allies if they paid their tribute, and that Caesar should remember they had never been defeated in battle. Caesar decided he must act immediately, especially when he heard that the Harudes were ravaging Aedui land and that a hundred clans of the Suebi were about to cross into Treveri territory.

He marched towards the Sequani town of Besancon which had natural defences and large military stores and to which the Germans were also heading. Having marched day and night, Caesar and his forces arrived first and fortified the town, acquired provisions and also information from the locals about the fear instilled by the Germans, which unnerved the Roman troops, mostly those with little experience of war, but their fear began to spread among more seasoned campaigners. Having summoned all the centurions, Caesar reprimanded them for doubting his leadership and Ariovistus’ friendship with Rome in the past which to date they had no reason to doubt and then reminded them of Roman victories over the Cimbri and Teutones under Marius, over Spartacus’ slave uprising under Crassus and that the Helvetii, whom they had recently defeated, had defeated these same Germans; Ariovistus’ victory over the Gauls was when the latter were exhausted and in separate groups. He reassured them about supplies and was in no doubt the troops would obey him as he had a reputation for integrity and success in battle; he would test that obedience that very evening when he intended to move camp with the tenth legion, with or without the rest of the troops. Caesar dramatically and resoundingly inspired all those present and in turn the troops.

Taking Diviacus’ advice, Caesar made a detour through open country, with forced marches for six days, until Ariovistus’ forces were only twenty three miles away. Ariovistus instigated a meeting between himself and Caesar, and, fearing a trap, he insisted Caesar should not bring any infantry. Caesar did not trust him and decided to mount the tenth legion on the cavalry’s horses. They met at a mound equidistant from the two camps, each with a ten men escort, with their cavalry three hundred yards away. Caesar reminded Ariovistus of the favours the Romans had conferred on him, that the Aedui were longstanding and trusted Roman allies and so he repeated his previous demands: that Ariovistus should not attack the Aedui, he should return the hostages and not allow any more Germans to cross the Rhine. Ariovistus’ reply was that the Gauls had invited him, he had demanded tribute when they had attacked him, the hostages had been given voluntarily, the large numbers of Germans coming into Gaul were for his protection and it was the Romans who were invading his part of Gaul; the Aedui had not helped the Romans in the recent revolt of the Allobroges and neither did the Romans help the Aedui in the war against the Sequani and Germans; he ended by saying there were many Romans who would thank him if he killed Caesar.

As the arguments continued, Caesar was informed that Ariovistus’ cavalry were approaching the mound and throwing stones and javelins but he forbade any retaliation. He refused a second meeting but when in his place he sent two trusted individuals, Proculus and Metius, Ariovistus had them put in chains, moved his camp nearer to Caesar’s and cut off supplies to the Romans but did not directly engage with the Romans, although they lined up for battle every day, apart from a few cavalry skirmishes. As he needed supplies, Caesar built another camp beyond Ariovistus’ and left two legions and auxiliaries to guard it. The next day Ariovistus attacked this smaller camp with neither side proving superior. As Caesar was perplexed as to why Ariovistus would not engage fully in battle, he was told that German women who engaged in divination had predicted the Germans would not win if they fought before the full moon.

Caesar took his opportunity, forcing the Germans to fight after leading his legions to Ariovistus’ camp. Both sides fought keenly in hand-to-hand fighting, the Romans routing the Germans on the left but were hard pressed on the right until P. Crassus, a cavalry officer, sent Roman reinforcements which turned the battle in the Romans’ favour. The routed Germans fled to the Rhine, fifteen miles away, most of whom were chased and killed by Roman cavalry. Ariovistus escaped in a small boat but his two wives and one of his daughters were killed; the other daughter was captured. Proculus and Metius were rescued. The Suebi, who were at the Rhine, ready to cross into Gaul, turned back and many of them were killed by other German tribes.

Caesar had therefore conducted two successful campaigns during the summer of 58BC. He left his army in winter quarters in Sequani country under the command of Labienus and left for northern Italy.

Overview Book II