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.
The Helvetii Move Towards Gaul
On the other hand, the party in Gaul hostile to the Romans, which hoped to obtain a powerful reinforcement in the Helvetii, more especially the Haeduan Dumnorix brother of Divitiacus, and at the head of the national party in his canton as the latter wasat the head of the Romans, procured for them a passage through the passes of the Jura and the territory of the Sequani. The Romans had no legal title to forbid this; but other and higher interestswereat stake for them in the Helvetic expedition than the question of the formal integrity of the Roman territory-- interests which could only be guarded, if Caesar, instead of confining himself, as all the governors of the senate and even Marius(34) had done, to the modest task of watching the frontier, should cross what had hitherto been the frontier at the head of a considerable army. Caesar was general not of the senate, but of the state; he showed no hesitation. He had immediately proceeded from Genava in person to Italy, and with characteristic speed brought up the three legions cantoned there as well as two newly-formed legions of recruits.
The Helvetian War
These troops he united with the corps stationed at Genava, and crossed the Rhone with his whole force. His unexpected appearance in the territory of the Haedui naturally at once restored the Roman party there to power, which was not unimportant as regarded supplies. He found the Helvetii employed in crossing the Saone, and moving from the territory of the Sequani into that of the Haedui; those of them that were still on the left bank of the Saone, especially the corps of the Tigorini, were caught and destroyed by the Romans rapidly advancing. The bulk of the expedition, however, had already crossed to the right bank of the river; Caesar followed them and in twenty-four hours effected the passage, which the unwieldy host of the Helvetii had not been able to accomplish in twenty days. The Helvetii, prevented by this passage of the river on the part of the Roman army from continuing their march westward, turned in a northerly direction, doubtless under the supposition that Caesar would not venture to follow them far into the interior of Gaul, and with the intention, if he should desist from following them, of turning again toward their proper destination. For fifteen days the Roman army marched behind that of the enemy at a distance of about four miles, clinging to its rear, and hoping for an advantageous opportunity of assailing the Helvetic host under conditions favourable to victory, and destroying it. But this moment came not: unwieldy as was the march of the Helvetic caravan, the leaders knew how to guard against a surprise, and appeared to be copiously provided with supplies as well as most accurately informed by their spies of every event in the Roman camp. On the other hand the Romans began to suffer from want of necessaries, especially when the Helvetii removed from the Saone and the means of river-transport ceased. The non-arrival of the supplies promised by the Haedui, from which this embarrassment primarily arose, excited the more suspicion, as both armies were still moving about in their territory. Moreover the considerable Roman cavalry, numbering almost 4000 horse, proved utterly untrustworthy--which doubtless admitted of explanation, for they consisted almost wholly of Celtic horsemen, especially of the mounted retainers of the Haedui, under the command of Dumnorix the well-known enemy of the Romans, and Caesar himself had taken them over still more as hostages than as soldiers. There was good reason to believe that a defeat which they suffered at the hands of the far weaker Helvetic cavalry was occasioned by themselves, and that the enemy was informed by them of all occurrences in the Roman camp. The position of Caesar grew critical; it was becoming disagreeably evident, how much the Celtic patriot party could effect even with the Haedui in spite of their official alliance with Rome, and of the distinctive interests of this canton inclining it towards the Romans; what was to be the issue, if they ventured deeper and deeper into a country full of excitement, and if they removed daily farther from their means of communication? The armies were just marching past Bibracte (Autun), the capital of the Haedui, at a moderate distance; Caesar resolved to seize this important place by force before he continued his march into the interior; and it is very possible, that he intended to desist altogether from farther pursuit and to establish himself in Bibracte.