This is Caesar’s explanation for the migration, a product of the tribe’s desire for greater opportunity to raid and the personal ambition of Orgetorix. Not all scholars have been willing to accept this at face value and have suggested that he concealed the truth in order to justify his own subsequent actions. They note, for instance, that the Commentaries make no mention of Ariovistus, the Germanic king who had fought for the Sequani and subsequently settled in their lands. This leads to the suggestion that the main intention of the Helvetii was to assist the other tribes in defeating Ariovistus and his Germans. In Caesar’s own consulship the German leader was named a ‘friend of the Roman people’ by the Senate and those fond of conspiracies suggest that he needed the neutrality or even complicity of Ariovistus to deal with the Helvetii in 58 BC. Once they had been defeated, he cynically turned on the German and drove him from Gaul. In this version, Caesar did not want the Helvetii to evict Ariovistus and so deny him the excuse for intervention in Gaul.6
None of this is convincing, for it is mainly reliant on hindsight. In the first place it is inherently unlikely that Caesar could have got away with such a massive distortion of the facts in his account, given that this was subject to hostile – and often informed-criticism. It is also unlikely that Rome would have viewed the expulsion of Ariovistus by the Helvetii entirely favourably. Their province of Transalpine Gaul was at present bordered by the Aedui and Sequani, both of whom had allied status. Ariovistus had recently been brought into the system. The province itself had just suffered a major rebellion on the part of the Allobroges and ideally required a period of stability if trade and revenue were not to suffer. The arrival of a strong tribe threatened to disturb this existing network of alliances. There was also the question of what would happen to the Helvetii’s own homeland once they left. If the abandoned land were then settled by newcomers, perhaps from one of the German tribes, then this might pose a new threat to the Roman province. On the whole the Romans were suspicious of the movements of peoples, so common in Iron Age Europe, and sought to prevent these from occurring in the lands near to their own provinces. Nor was it in their interest for the tribes of Gaul to unite independently of Rome.
Therefore Caesar would have had ample justification for intervention even if the Helvetii had intended to fight Ariovistus, and did not need to conceal this. On balance, his own account is far more plausible. Casticus and Dumnorix clearly both believed that they would gain from the arrival of the migrants, and doubtless expected support from Orgetorix against all their opponents, whether foreign or within their own tribe. Those leaders of the Sequani who had invited Ariovistus into Gaul in the first place, and the many chieftains who would appeal to Caesar for aid over the coming years, acted with the same motives. Association with a strong external force boosted a chieftain’s prestige, and might well be converted into direct military assistance. It is misleading to speak of pro – or anti – Roman factions within the tribes – or for that matter pro – or anti – German or Helvetian groups. Each individual leader sought whatever aid he believed would be of most benefit to him, and all were engaged in the struggle for dominance within the tribe. Some leaders, and indeed the ruling councils of some tribes, decided that they were better off allied to Caesar and Rome, while other men and peoples who were their rivals acted differently.7
Yet in the spring of 58 BC there is every sign that Caesar was wrong-footed by the Helvetii. Perhaps he had been surprised by the timing of the migration, or maybe its sheer scale. He had four legions at his command, but only one of these was in Transalpine Gaul. The remaining three were camped near Aquileia on the border of Cisalpine Gaul nearest to Illyricum. It is not known who stationed the troops there, but even if it had not been Caesar, then he had made no effort to alter this disposition. Even when he hastened to the Rhône he made no effort to send new orders to these troops. It is hard to avoid the conclusion that he was still thinking very much in terms of a Balkan campaign. Perhaps it was only when he arrived near Geneva that he appreciated the full scale of the problem. The Helvetii and the allied clans who joined them in the migration had piled their possessions into wagons and set off with great purpose. Behind them they left the smouldering ruins of their towns and villages, deliberately put to the torch to discourage anyone from wavering if the journey became difficult. Caesar may have exaggerated when he claimed that every single settlement was burned, and indeed in the implication that not a single tribesman remained behind, but the upheaval was clearly a massive one.
The figure of 368,000 migrants was said by Caesar to have been taken from captured records that the Helvetii themselves had made using Greek characters – Gallo – Greek inscriptions using the Celtic language but Greek alphabet are fairly common finds from southern Gaul and attest to the long presence and influence of Massilia. Any numbers found in an ancient text must always be treated with a degree of caution, since it is so easy for them to become distorted over the centuries as manuscripts were copied and recopied. In cases of this sort, the Roman desire to quantify military victory in the numbers of enemies killed and cities captured encouraged deliberate exaggeration. It is certainly a very high figure, suggesting a density of population considerably higher than would be expected, even in a region so overcrowded as to produce a migration. Yet in the end we know so little about ancient levels of population that it is unwise to be too dogmatic, and if we reject Caesar’s figure then we have nothing with which to replace it. Modern suggestions of more ‘plausible’ totals can never be anything more than conjectural. In the end, even if Caesar did exaggerate, or was genuinely mistaken, a substantial number of people and animals were on the move, probably in many separate parties rather than one immensely long column, which would have presented huge practical and logistical problems. However, at certain points, such as river crossings and mountain passes, there would have been a tendency for the different groups to cluster closer to each other.8
Caesar is unlikely to have known precisely how many migrants were waiting to cross the river into his province, but they certainly far outnumbered the single legion he had at his disposal. One of his first orders instructed the legionaries to break down the bridge crossing the river at Geneva. He also levied as many troops as he could find in the province, the tribes there providing him with contingents of cavalry. Soon after his arrival he was visited by a delegation of Helvetian leaders who asked permission for their people to move through the Roman province, promising that they would not plunder as they went. Caesar was unwilling to grant the request. In the Commentaries he takes this opportunity to remind his audience of a battle some fifty years earlier, when one of the clans of the Helvetii had defeated a Roman army. From a Roman viewpoint this had been an unprovoked attack, made worse when the survivors were forced to undergo the humiliation of passing under a yoke of spears, symbolising their loss of warrior status. This had been in 107 BC, in the midst of a series of disasters inflicted on Roman armies by the Cimbri and Teutones. Caesar wished to revive the fear of those years-something which was still just within living memory-amongst his Roman audience. They could then be reassured that Marius’ nephew was there to defend them.
Yet at the beginning Caesar did not have the means to do this. Instead he played for time, telling the Helvetian representatives that he would consider the matter, and inform them of his decision if they returned on the Ides-the 13th – of April, which was probably in one or two weeks time. During the interval he set the legion to constructing a line of defences running along the Roman bank of the Rhône from Lake Geneva to the edge of the Jura Mountains. It was the first of many engineering feats that his army would perform and was swiftly accomplished. For 19 Roman miles (each somewhat shorter than the modern mile at 1,618½ yards or 1.48 km) they raised an earth rampart some 16 feet high. This was strengthened at key points where the river could be forded by forts garrisoned by detachments of the legion and the other troops Caesar had raised. It is possible that the rampart was not absolutely continuous, having gaps whenever
natural features ensured that it was impossible to cross, but there is insufficient evidence to confim this suggestion. Such a line was not a novel concept for a Roman army in this period. Crassus had made use of a similar fortified barrier in the campaign against Spartacus, and Pompey had done the same in the Mithridatic War. Such lines were practical, presenting an obstacle that would at the very least slow down an enemy, but also were a strong visible statement of intent and determination.9
When the Helvetii returned for Caesar’s decision, he bluntly informed them that ‘according to the custom and precedent of the Roman People, he could not permit anyone to journey through the province, and that he would stop them if they tried to force their way through’.10 The new fortifications were there to demonstrate that he meant what he said. However, it was difficult for such a great mass of people suddenly to change direction and purpose. The period of waiting by the river had also probably been very frustrating and many of the Helvetii were determined to keep going, especially after the years of preparation and the willing destruction of their old homes. Small groups began to cross the Rhône, either using the fords or rigging up rafts to carry themselves, their animals and vehicles. It is possible that these were deliberate probes sent by the chieftains to test the strength of Caesar’s defences, but more likely that they reflected the loose central authority and individual independence that seems to have been characteristic of many of the tribes of Gaul. They were certainly not full-fledged assaults on the line of fortifications. Most of the crossings took place under cover of darkness, but a few parties were bold enough to risk the attempt in daylight. None succeeded, for Caesar’s men were able to concentrate and meet each group in turn, overwhelming many of them with missiles as they struggled to cross. Eventually the Helvetii admitted defeat, but by this time some of their leaders had decided on another course, taking the alternative, more difficult route out of their lands. This meant taking the passes through the Jura Mountains into the lands of the Sequani. It would not have been practical if the latter had decided to resist them, but the tribe was persuaded by Dumnorix the Aeduan to let the Helvetii through. He was presumably able to do this through his own reputation and some of his many marriage connections with powerful men. Orgetorix was dead, but it would still be useful for Dumnorix to be able to call on the support of the powerful Helvetii once they were established in their own lands. Even before they began to lumber off in this new direction, Caesar received reports of their plans.11
‘A NEW WAR’
It was probably at this point that Caesar finally resolved on a full campaign in Gaul against the Helvetii. The reason he gave in the Commentaries was that the Helvetii planned to settle ‘on the borders of the Santones, who lived not far away from the borders of the Tolosates, a tribe within the province. He understood that if this occurred, it would put the province in great danger, with many warriors, hostile to the Roman people, living close by a region which produced a rich harvest of grain, but was undefended.’ His own recent actions had ensured the hostility of the Helvetii, but from a Roman standpoint his reasoning was sound. As we have seen, at the very least the incursion of the new settlers would have upset the existing balance system where a combination of Roman diplomacy and military strength had ensured the security of the province. Leaving his senior legate Labienus in charge of the defences on the Rhône-probably another indication that the Helvetii were travelling in lots of separate groups, and that it took time for such a sprawling mass of people, animals and vehicles to move off in a new direction – Caesar hastened to Aquileia and his main army. Two new legions, the Eleventh and Twelfth, were enrolled to add to the three already stationed there and the one left behind on the Rhône.
The Commentaries give the impression that this was only done on Caesar’s arrival, but the practicalities of recruitment and organisation make it more likely that he had already given the order for this some time before. The troops may originally have been intended to strengthen the army for operations in the Balkans, but the immediate threat of the Helvetii provided a better pretext for his audience. He had no authority to raise new legions, for only the Senate was supposed to instruct a governor to do this, but lack of specific power had never stopped Caesar in the past. As a youth and a private citizen he had raised allied troops to combat the pirates and oppose the Pontic invasion of Asia, while he had also raised ten cohorts-equivalent in numbers to a legion-during his term as propraetor in Spain. Never doubting that he knew what was in the interest of Rome and the provinces, Caesar simply acted and then trusted in his own ability to make things work. Since it had not authorised their existence, the Senate would not provide money from the Treasury to pay and supply the new legions, which meant that the proconsul would have to find the funds to do this from the revenue he raised in his province and any profits to come from victories. The bulk of the soldiers in the new formations were almost certainly from Cisalpine Gaul and so not actually Roman citizens and therefore legally ineligible for service in a legion. In the past Caesar had championed the desire of the population of the region for enfranchisement, and as governor he consistently treated them as if they were in fact citizens. This was the first major example of this deliberate policy.12
Soon, Caesar was ready to lead all five legions back to Transalpine Gaul. The quickest route was through the Alps, which although largely surrounded by Roman provinces was still unconquered. In a week the Roman column crossed the mountains, beating off successive ambushes from the fiercely independent tribes who resented this incursion and doubtless also saw the welcome opportunity for gaining some plunder. It was a harsh introduction to campaigning for the raw recruits, but the march seems to have been made without serious loss. Once over the mountains Caesar moved into the territory of the Allobroges, joining up with the troops he had left in the province. He now had six legions at his disposal, with a total of something like 25,000 – 30,000 men, and a force of allied cavalry that would soon muster about 4,000 men, along with some light infantry. Added to this were the slaves who accompanied each legion to care for the baggage train, doubtless some also owned by the officers, and quite possibly also some camp followers. All of these needed to be fed, as did the thousands of cavalry mounts and draught and pack animals. Keeping his army supplied has always been one of the first concerns of any army commander. The operations against the Helvetii had developed so unexpectedly that Caesar had had little opportunity to prepare for this task by massing all that he needed in conveniently placed supply dumps in Transalpine Gaul. The main force is unlikely to have brought substantial supplies of food with it in its rapid march from Aquileia. It was still only spring, and the harvest would not become available for some months – Caesar notes in the Commentaries that it occurred late in these northern climes-so that the army could not expect to gather too much of what it needed from the land it marched through. Therefore messages went to Rome’s allies, particularly the large and powerful Aedui, to gather stocks of grain and make them available for his troops.
In the meantime the Helvetii had crossed through the Pas de l’Ecluse into the lands of the Sequani and were entering the borderland of the Aedui. Representatives of the tribe came to Caesar complaining of plundering attacks by the migrants. ‘The Aedui had always deserved well and that it is not right for our lands to be devastated, our children carried off into bondage, and our towns to be sacked almost under the eyes of a Roman army’ Similar complaints also came in from the Ambarri, a tribe allied to the Aedui, and the Allobroges, who had not that long before rebelled and been defeated. It is unknown whether or not the leaders of the Helvetii had consciously decided to launch these plundering attacks. Even if they had not, it would have been extremely difficult to control such a large and disparate group broken up into many individual parties. Given the delays imposed on their journey, some of the migrants may have been running short of supplies. Equally the hostility could have begun with the local peoples, nervous of the incursion of so many strangers. That violence resulted was unsurpris
ing, but the need to defend or gain revenge for attacks on an ally was for the Romans a classic justification for aggressive warfare. It should also be said that this made practical sense. If Rome was unwilling or unable to guard its friends, then why should any tribe, especially the so recently discontented Allobroges, feel that it was worth maintaining the alliance? As consul, Caesar had passed a law regulating the behaviour of provincial governors and restricting their freedom to lead their army outside their province. In the Commentaries he demonstrated that it was entirely right for him to do just that.13
Caesar caught up with the migrants near the Saône. For twenty days the tribesmen had been ferrying themselves across the river on rafts and small boats lashed together, and three-quarters of them were already on the far bank. It was another indication that we should not think of the Helvetii as moving in one ordered column, but in many separate groups spread over the landscape and only bunching when the path became narrow. Still on the same side of the river as the Romans were the Tigurini, the clan that had been responsible for the humiliating defeat of the Romans in 107 BC. Caesar makes sure that he reminds his readers of this defeat once again, and adds that he had a personal stake in avenging it, since the grandfather of his father-in-law Calpurnius Piso had died in the battle. After his scouts had reported this to Caesar, he decided on a surprise attack, leading his army out before dawn. The result was not a battle, but a massacre, as the Romans fell upon the scattered and unsuspecting groups of tribesmen and their families. Many were killed and the rest dispersed, abandoning their wagons and possessions. The Romans then bridged the Saône and crossed it in a single day.14
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