This was a wise move, for it was clear from reports on the spot that the whole Belgic confederacy, representing the most warlike of the Gallic tribes, were up in arms. The fate of Ariovistus, the year before, had shown that the only way to resist the extension of Roman rule in Gaul was by tribal combination. The Belgæ thoroughly realized their danger, and when Cæsar passed their frontiers, they opposed him with a large allied army composed of contingents of all the neighboring peoples.
The great difficulty was to keep such large masses of men together and to provide them with food. In the time of Marius, the Germanic invaders, the Cimbri and the Teutones, in order to secure provisions as they went, had divided into several smaller groups, each one of which was beaten in detail by the Roman general. Cæsar’s strategy was to be governed by the same principles; he meant to wear the Belgæ out and to refuse to give battle until they had lost their unity, until each dissevered fraction might be drawn into action without support from the rest. Cæsar having recruited two new legions, in all there were eight. Besides, there served under him a variegated band of allies, Numidians, Cretans, men of the Balearic Islands, and Gallic cavalry.
Altogether the Roman fighting host may be reckoned at fifty to sixty thousand men, with camp followers, perhaps nearly one hundred thousand in all. To keep such a body in the field for a considerable time meant a carefully organized system of transportation and economic equipment. A strongly fortified camp was constructed on the north bank of the River Aisne, where the soldiers were kept in good discipline. The remains of extensive fortifications, in the form of ditches eighteen feet wide and nine or ten feet deep, and a wall with palisades twelve feet high, were found on the site of Cæsar’s camp by the archæologists who worked under the direction of Napoleon III.
The camp was in the country of the Remi, who had, as we have mentioned, become allies of the Romans; it was their town Bibrax which the Belgæ first attacked, hoping to induce Cæsar to leave his fortified position to repel them. He remained, however, where he was, sending sufficient help in the way of defensive artillery to enable the townsmen to defend themselves and to force the Belgæ to give up the siege. They then turned to attack the Roman camp. Cæsar drew up his army, but neither side had any desire to come to close quarters, as in front of the camp there was a considerable stretch of swampy ground. The Belgæ then tried to cut off the Roman line of communications, but this involved crossing the Aisne, and its banks were closely watched by Cæsar’s men. A few horsemen and war engines were sufficient to deter them from making the attempt.
If the Belgæ had crossed with their whole army, they could have carried out their purpose; the Roman communications would have been broken, but the Romans could have gone ahead, and the Belgæ, outside of their own land, had no way of maintaining their supplies. The only thing to do was to surround the Roman camp from all sides and starve it out. Even with their superior numbers, which Cæsar gives as 306,000, this was a difficult operation, for the enveloping lines, owing to the country being traversed by two rivers, would have been large. In any case the Belgæ recognized that they could not keep the field long, and when they heard that Cæsar’s allies, the Ædui, were invading their country, they decided to withdraw, the confederated tribes engaging to help one another if Cæsar’s army invaded their territory. The retreat of the Belgæ was so unexpected that at first the Romans took it for a feint meant to provoke them to leave their camp.
As soon as the news was well authenticated, the cavalry pursued the retreating barbarians, keeping up a series of irritating attacks. The Belgic strongholds surrendered soon after; only three tribes, the Nervii, the Viromandui, and the Atrebates, tried to strike a blow for Gallic freedom. They fell upon the Romans, while they were arranging to encamp in a woody country on the Sambre, and caused almost a panic. The allied troops fled in confusion, but the legionaries held their ground, getting themselves in line, and as they were far superior in numbers to the Nervii, they soon got the upper hand of them, although there was some sharp fighting and for a time two of the legions were hard pressed. It was part of the Roman general’s strategy not to face a superior force. This point is apparent in the previous campaigns, but, as a military writer, Cæsar had no scruples in manipulating his figures for popular consumption. When the Nervii made peace unconditionally, they represented themselves, according to Cæsar, as having only 500 men left out of an original 60,000 capable of bearing arms; a few years later they appear again in the Commentaries as having a considerable army. They also sent a contingent of 5000 to Alesia at the close of the Gallic war. Probably a just estimate of the fighting force of the Nervii would give them 30,000 men, because the whole population of the district could hardly have been more than 150,000 souls. They occupied a territory of four hundred square kilometers, and with the slight density of population in Gaul, they could not have numbered more than the figures given above. Even in the Italian peninsula, which was more thickly settled, there was altogether a population of not more than three and a half millions and a density of only twenty-five per square kilometer. The Roman legions who opposed the Nervii in this last fight numbered at least 40,000 men.
Dwelling east of the Nervii were the Aduatuci, said to be descendants of the survivors of the former Cimbri and Teutones, whom Marius had destroyed. They had promised to help the Nervii, but had come too late for the battle. Now they withdrew to their chief fortress, but when they saw themselves being enveloped in the complicated and scientific siege works of the Romans, their hearts failed and they surrendered before the final assault was made. What they had not been able to do openly they hoped to accomplish by treachery, for they reserved a part of their arms, at the time they made their submission, and when the Romans were off their guard at night, made a sudden attack upon them. They were defeated with heavy loss, and the next day, in order to make an example of them, Cæsar sold the whole tribe, men, women, and children, into slavery, 53,000 souls in all.
After the Belgic campaign was over, Cæsar laid plans for the further expansion of Roman control in Gaul by sending one of his lieutenants to Armorica, modern Normandy and Brittany, to secure the submission of the inhabitants. Moreover, seven legions were placed in winter quarters along the Loire, ready to use the stream to transport themselves to the territory of the Veneti, the chief tribe in the west of Gaul. (56 B.C.)
The announcement of Cæsar’s great success made a profound impression in Rome; new and unknown domains were being annexed, and the people were granted an unprecedented space of fifteen days for a public thanksgiving. During the winter the general himself took up the detailed work of governor of the Cisalpine province, and also made a tour of Illyria, which had been previously unvisited by him. It was filled with a hardy and brave population and might well be used for drawing auxiliary troops for his army.
In Gaul the situation of affairs showed that the people of Armorica could not be depended upon, though they professed loyalty to the Romans. Young Crassus, who commanded a garrison encamped at the mouth of the Loire, when he found his soldiers suffering from lack of supplies, sent some of his officers to collect provisions from the neighboring districts supposedly friendly. The Veneti seized these men, and refused to give them up except in exchange for their own hostages in the hands of the Romans, and they proceeded to bind themselves together for common action, showing their desire to repudiate the sovereignty of Rome. Cæsar’s reply to the challenge was to order the preparation of a fleet of ships to be put into service the following summer against the Veneti, whose chief seats were along the sea coast.