Fifteen days after the legions entered winter quarters the first uprising broke out under the leadership of Ambiorix and Catuvolcus, the rulers of the Eburones. Caesar claims that the instigator of the revolt was Indutiomarus, who had good reasons to hate Caesar who had favoured his rival earlier in the year. It seems likely that the he saw the uprising as a prelude to a general rebellion against the Romans. Although Caesar presents it as the product of an individual noble’s resentment, the response of the Eburones and then of other tribes indicates that hatred for Rome was widespread. At first the Eburones had welcomed Caesar’s legates Cotta and Sabinus and supplied their camp at Atuatuca (the location is unknown, but perhaps in the neighbourhood of Liège or Tongres) with grain, but Indutiomarus changed all that. An attack was made on soldiers gathering wood and then the Eburones began a siege of the Roman camp. The attack was driven off by a strong defence of the camp and a victorious sortie by Spanish cavalry. The Eburones then asked for a parlay to settle matters.

Cotta and Sabinus sent as their representative Gaius Arpineius, a Roman knight who was a close friend of Sabinus, and Junius, who had had frequent contacts with Ambiorix. Ambiorix spoke of the earlier benefits that Caesar had conferred on the Eburones and his family and claimed that the attack on the camp was not of his doing but that he had been compelled to act by his tribe. He said that the tribe had been induced to do so by a general conspiracy of the Gauls. They had planned to attack all of the Roman camps on a single day so that they could not come to each other’s aid. He had acted as duty demanded but felt that he owed a great deal to the Romans and he now wanted to repay their previous favours. He said that the situation would only grow worse. A great number of German mercenaries had been hired and had already crossed the Rhine. They would be here in two days. He asked that Cotta and Sabinus consider whether they should evacuate the camp and lead their men either to the camp of Labienus or Cicero, who was only about 45 miles away. If they did so he swore that he would give them safe passage.

The envoys reported back to Sabinus and Cotta, who were greatly disturbed by the news. The unimportance of the Eburones gave credence to the notion that the rebellion was in fact general, so they called a meeting of the military tribunes and the leading centurions to discuss the matter. It soon became apparent that the two legates held radically opposing views on what should be done. Cotta, with the support of many of the military tribunes and centurions, urged caution, saying that they should remain in camp unless Caesar ordered them to leave. He stressed that they had a sufficient supply of grain and that they would be able to hold off the Germans, as their defence against the Eburones had already shown. Help would come from the other camps and from Caesar. Finally, he pointed out that it was disgraceful to trust an enemy when lives were at stake.

Sabinus objected strongly. He argued that by the time their enemies had united with the Germans it would be too late, time would have run out. Caesar must have already left for Italy for neither the murder of Tasgetius nor the attack by the Eburones would have taken place if he had been present. He argued that, given the hatred of the Gauls and Germans for Rome, the only safety lay in flight. He argued that departure would be best: if the threat were not serious then they would reach the nearest legion in safety; if the danger was real escape was their only hope. If they endured a long siege where they were they were bound to suffer from hunger.

The argument between the two men and their supporters was long and vehement but in the end Cotta finally gave way and preparations for departure were begun. After packing all night the Romans finally left their camp at dawn (about 6.30am). Given the number of men and their heavy baggage the column stretched for quite a distance. The Gauls, aware of the departure because of the noise the column made, set up two ambushes in the woods through which the Romans had to pass and then awaited their arrival. When the column entered a deep ravine the Gauls appeared at both ends of it and began attacks on both its head and on the rearguard. The divided command complicated the Roman response. Sabinus tried to deploy the cohorts to meet the attack but seems to have been too unhinged to do so effectively. Cotta seems to have been more successful. Finally the commanders made a concerted response. Orders were given to abandon the baggage and to form a circle so as to be able to meet an attack from any quarter. This was a standard defensive formation when a battle line could not be deployed or when it had been broken. Caesar criticizes this manoeuvre because being on the defensive would weaken the legionaries’ morale and encourage the enemy’s, but it is hard to see what else the legates could have done in such a situation. The more serious problem was that in forming up the soldiers lost contact with their units and many of them tried to rescue those items most precious to them from the baggage, which disordered their lines. In essence the legates lost control of their troops. While the Romans had at least temporarily lost formation the Gallic leaders made every effort to preserve theirs. They exhorted their men to ignore the booty for the present, promising that they would distribute it after victory.

Caesar claims that their courage and fighting ability were equal to the Romans, who were handicapped by Sabinus’s incompetence. As always, in close fighting the Romans were superior and whenever a cohort advanced to the attack it inflicted heavy casualties. Ambiorix noting this ordered his men to keep their distance and to use missile weapons. When the Romans charged they should give ground and attack them as they returned to their positions. The same tactic would be used in the next year by the Parthians against Crassus at Carrhae in northern Mesopotamia. In addition, the charges by individual cohorts created gaps in the Roman line that exposed the Romans’ unshielded right side to attack. There was little advantage for the legionaries in maintaining their circular defensive formation. The dense mass meant that enemy missiles often found their targets and its immobility left the initiative to the enemy.

Sabinus finally asked for a parlay with Ambiorix and this was granted. He tried to persuade the wounded Cotta to accompany him but Cotta refused. He then ordered the military tribunes who were with him, as well as the senior centurions, to follow. As he approached Ambiorix he was ordered to drop his weapons, he did so and instructed his men to do the same. While discussions were being prolonged on purpose Sabinus and his men were surrounded and cut down.

Excited by this success the Gauls raised their battle cry and made an attack on the Roman lines, throwing them into disorder. Cotta died fighting along with most of his men. The survivors fled back to camp. With difficulty they held out until nightfall when they decided the situation was hopeless and they committed suicide. Only a few survived. Wandering along unknown trails they finally made their way to Labienus and told him what had happened. Some of these men must have been officers given Caesar’s account of the council of officers at which the decision was made to leave camp.

Atuatuca was one of the two serious defeats that Caesar suffered in Gaul; the other being Gergovia in 52. His narrative makes every effort to place the blame for it on the dead Sabinus. Given the deaths of perhaps 6,000 men this is understandable. However, the portrayal of Sabinus’s actions at Atuatuca is at variance with his previous record. He had played an important role in the battle at the Sabis, in command of a bridge over the river, and then had led Caesar’s favourite legion, the Tenth, in the final battle against the Nervii. In 56 during the war with the Veneti he was sent with three legions to the Venelli and waged a skilful and successful campaign against them. In the following year in conjunction with Cotta he fought the Menapii without achieving a decisive result. However, Caesar ascribes the lack of success not to any fault in generalship but to the nature of the terrain in which he campaigned. We know less about the prior career of Cotta. Besides his campaign with Sabinus he is mentioned in the preliminaries to the battle against the Nervii as co-commander of the cavalry. These facts create a suspicion that Sabinus was used as a scapegoat by Caesar to divert attention from his own responsibility for what happened. The newly raised legion and the additional five cohorts were posted in an area that Caesar knew to be a centre of unrest. Its lack of experience and the need to integrate the additional cohorts would require time and training. Given the possible dangers, such time might not be available. The attack by the Eburones soon after the Romans entered winter quarters makes it likely that there had been little opportunity to create a cohesive force. In addition, the Eburones had not been conquered by Caesar and must have felt resentful at the demand for grain and other supplies. The situation was further complicated by the divided command. It had led to disaster earlier in Roman history. As the account of the council shows, at the very least it led to a rivalry that could not have helped the troops’ morale. The argument between Cotta and Sabinus is not as clear-cut as Caesar presents it. The Romans were isolated in hostile territory with no certainty that if they held out in camp help would come. Caesar’s own reference to general unrest made Ambiorix’s claim of general rebellion plausible. His previous relations with Caesar gave some credibility to the claim that he had been forced into attacking the camp and would help the legionaries leave. Given these considerations Sabinus’s arguments were sensible. After the Romans had marched out of their camp the one obvious failing of both commanders was the lack of adequate scouting. Once the men were trapped in the ravine their position was hopeless and the attempt by Sabinus to negotiate was more sensible than Caesar makes it appear, as there was no obvious alternative. In addition, the panic ascribed to him during the battle had little effect on its course. Once the army was trapped nothing beyond the enemy’s agreement to let it through would have made a difference. By placing the blame squarely on Sabinus Caesar minimizes his own role in the debacle. To position a relatively-untried legion in an area that was restive was a mistake. Clearly Caesar was aware of the unrest. He remained in Transalpine Gaul far longer than he usually did. Despite his references to Gallic unrest he seems to have underestimated the immediate threat. It would have made more sense to assign the unit to a peaceful area, as he had done with the legion under Roscius’s command. It is significant that the second attack that year against a Roman camp took place in the same area.