The German warrior-prince naturally took this as a renunciation by the Romans of the Celtic land which they had not occupied; he accordingly took up his abode there, and began to establish a German principality on Gallic soil. It was his intention that the numerous bands which he had brought with him, and the still more numerous bands that afterwards followed at his call from home - it was reckoned that up to 696 some 120,000 Germans had crossed the Rhine - this whole mighty immigration of the German nation, which poured through the once opened sluices like a stream over the beautiful west, should become settled there and form a basis on which he might build his dominion over Gaul. The extent of the German settlements which he called into existence on the left bank of the Rhine cannot be determined; beyond doubt it was great, and his projects were far greater still. The Celts were treated by him as a wholly subjugated nation, and no distinction was made between the several cantons. Even the Sequani, as whose hired commander-in-chief he had crossed the Rhine, were obliged, as if they were vanquished enemies, to cede to him for his people a third of their territory - presumably upper Alsace afterwards inhabited by the Triboci - where Ariovistus permanently settled with his followers; nay, as if this were not enough, a second third was afterwards demanded of them for the Harudes who arrived subsequently. Ariovistus seemed as if he wished to take up in Gaul the part of Philip of Macedonia, and to play the master over the Celts who were friendly to the Germans no less than over those who adhered to the Romans.
Spread of the Helvetian Invasion to the Interior of Gaul The appearance of the energetic German prince in so dangerous proximity, which could not but in itself excite the most serious apprehension in the Romans, appeared still more threatening, inasmuch as it stood by no means alone. The Usipetes and Tencteri settled on the right bank of the Rhine, weary of the incessant devastation of their territory by the overbearing Suebian tribes, had, the year before Caesar arrived in Gaul (695), set out from their previous abodes to seek others at the mouth of the Rhine.
They had already taken away from the Menapii there the portion of their territory situated on the right bank, and it might be foreseen that they would make the attempt to establish themselves also on the left. Suebian bands, moreover, assembled between Cologne and Mayence, and threatened to appear as uninvited guests in the opposite Celtic canton of the Treveri. Lastly, the territory of the most easterly clan of the Celts, the warlike and numerous Helvetii, was visited with growing frequency by the Germans, so that the Helvetii, who perhaps even apart from this were suffering from over-population through the reflux of their settlers from the territory which they had lost to the north of the Rhine, and besides were liable to be completely isolated from their kinsmen by the settlement of Ariovistus in the territory of the Sequani, conceived the desperate resolution of voluntarily evacuating the territory hitherto in their possession to the Germans, and acquiring larger and more fertile abodes to the west of the Jura, along with, if possible, the hegemony in the interior of Gaul - a plan which some of their districts had already formed and attempted to execute during the Cimbrian invasion[32].
the Rauraci whose territory (Basle and southern Alsace) was similarly threatened, the remains, moreover, of the Boii who had already at an earlier period been compelled by the Germans to forsake their homes and were now unsettled wanderers, and other smaller tribes, made common cause with the Helvetii. As early as 693 their flying parties came over the Jura and even as far as the Roman province; their departure itself could not be much longer delayed; inevitably German settlers would then advance into the important region between the lakes of Constance and Geneva forsaken by its defenders. From the sources of the Rhine to the Atlantic Ocean the German tribes were in motion; the whole line of the Rhine was threatened by them; it was a moment like that when the Alamanni and the Franks threw themselves on the falling empire of the Caesars; and even now there seemed on the eve of being carried into effect against the Celts that very movement which was successful five hundred years afterwards against the Romans.
Under these circumstances the new governor Gaius Caesar arrived in the spring of 696 in Narbonese Gaul, which had been added by decree of the senate to his original province embracing Cisalpine Gaul along with Istria and Dalmatia. His office, which was committed to him first for five years (to the end of 700), then in 699 for five more (to the end of 705), gave him the right to nominate ten lieutenants of propraetorian rank, and (at least according to his own interpretation) to fill up his legions, or even to form new ones at his discretion out of the burgess-population - who were especially numerous in Cisalpine Gaul - of the territory under his sway. The army, which he received in the two provinces, consisted, as regards infantry of the line, of four legions trained and inured to war, the seventh, eighth, ninth, and tenth, or at the utmost 24,000 men, to which fell to be added, as usual, the contingents of the subjects. The cavalry and light-armed troops, moreover, were represented by horsemen from Spain, and by Numidian, Cretan, and Balearic archers and slingers. The staff of Caesar - the elite of the democracy of the capital - contained, along with not a few useless young men of rank, some able officers, such as Publius Crassus the younger son of the old political ally of Caesar, and Titus Labienus, who followed the chief of the democracy as a faithful adjutant from the Forum to the battle-field. Caesar had not received definite instructions; to one who was discerning and courageous these were implied in the circumstances with which he had to deal. Here too the negligence of the senate had to be retrieved, and first of all the stream of migration of the German peoples had to be checked.
Just at this time the Helvetic invasion, which was closely interwoven with the German and had been in preparation for years, began. That they might not make a grant of their abandoned huts to the Germans and might render their own return impossible, the Helvetii had burnt their towns and villages; and their long trains of waggons, laden with women, children, and the best part of their moveables, arrived from all sides at the Leman lake near Genava (Geneva), where they and their comrades had fixed their rendezvous for the 28th of March[33] of this year. According to their own reckoning the whole body consisted of 368,000 persons, of whom about a fourth part were able to bear arms. As the mountain chain of the Jura, stretching from the Rhine to the Rhone, almost completely closed in the Helvetic country towards the west, and its narrow defiles were as ill adapted for the passage of such a caravan as they were well adapted for defence, the leaders had resolved to go round in a southerly direction, and to open up for themselves a way to the west at the point, where the Rhone has broken through the mountain-chain between the south-western and highest part of the Jura and the Savoy mountains, near the modern Fort de l'Ecluse. But on the right bank here the rocks and precipices come so close to the river that there remained only a narrow path which could easily be blocked up, and the Sequani, to whom this bank belonged, could with ease intercept the route of the Helvetii. They preferred therefore to pass over, above the point where the Rhone breaks through, to the left Allobrogian bank, with the view of regaining the right bank further down the stream where the Rhone enters the plain, and then marching on towards the level west of Gaul; there the fertile canton of the Santones (Saintonge, the valley of the Charente) on the Atlantic Ocean was selected by the wanderers for their new abode. This march led, where it touched the left bank of the Rhone, through Roman territory; and Caesar, otherwise not disposed to acquiesce in the establishment of the Helvetii in western Gaul, was firmly resolved not to permit their passage. But of his four legions three were stationed far off at Aquileia; although he called out in haste the militia of the Transalpine province, it seemed scarcely possible with so small a force to hinder the innumerable Celtic host from crossing the Rhone, between its exit from the Leman lake at Geneva and the point of its breaking through the mountains, over a distance of more than fourteen miles. Caesar, however, by negotiations with the Helvetii, who would gladly have effected by peaceable means the crossing of the river and the march through the Allobrogian territory, gained a respite of fifteen days, which was employed in breaking down the bridge over the Rhone at Genava, and barring the southern bank of the Rhone against the enemy by an entrenchment nearly nineteen miles long: it was the first application of the system - afterwards carried out on so immense a scale by the Romans - of guarding the frontier of the empire in a military point of view by a chain of forts placed in connection with each other by ramparts and ditches. The attempts of the Helvetii to gain the other bank at different places in boats or by means of fords were successfully frustrated by the Romans in these lines, and the Helvetii were compelled to desist from the passage of the Rhone.