By rendering the passage of the Rhone impossible, and by binding to his cause the peoples who occupied the whole course of the Saône, from Pontailler to near Trévoux, he had cut off from the Helvetii the road to the south, and thrown difficulties in their way towards the west. Still, these persisted none the less in their design; they made an arrangement with the people of Franche-Comté, to whom the passage of the Pas-de-l’Ecluse belonged, to debouch by that defile into the plains of Ambérieux and on the plateau of the Dombes. They could thus arrive at the Saône, pass it peaceably or by force, proceed into the valley of the Loire by crossing the mountains of Charolais, and penetrate thence into Saintonge. As soon as Cæsar was aware of this project, he immediately decided on his course of action: he foresaw that a long time would elapse before the Helvetii effected a passage across the unquiet countries of so many hosts; he reckons that an agglomeration of 368,000 individuals, men, women, and children, carrying three months’ provisions in wagons, would be slow to move; he repairs to the Cisalpine, raises two legions there, sends to Aquileia for the three who were in winter quarters there, and, crossing the Alps again, arrives, two months afterwards, at the confluence of the Rhone and the Saône, on the heights of Sathonay. He learns that the Helvetii have been employed during twenty days in crossing the Saône between Trévoux and Villefranche, but that a part of them still remain on the left bank; seizes the opportunity, attacks the latter, defeats them, and thus diminishes the number of his adversaries by one-fourth; then, crossing the Saône, he follows during fifteen days the mass of the Helvetian emigration, which was advancing towards the sources of the Bourbince. As he finds himself in want of provisions, he turns off from his road, and marches towards Bibracte (_Mont Beuvray_), the citadel and principal town of the Burgundians. This march to the right leads the Helvetii to believe that he is afraid of encountering them; they then march back, and attack him unexpectedly; a great battle is fought, and, with his four old legions only, Cæsar gains the victory. The immigration, already considerably diminished by the battle of the Saône, no longer counts more than 130,000 individuals, who make their retreat towards the country of Langres. The Roman general does not pursue them; he remains three days burying the dead and attending to the wounded. But his influence is already so great, that, to deprive the wreck of the vanquished army of provisions, he has only to give orders to the peoples whose territory they cross. Deprived of all resources, the fugitives discontinue their march, and make their submission. He hastens to overtake them towards Tonnerre. When he arrives in the midst of them, he adopts a generous policy, and gains, by his generous behaviour, those whom he had subjugated by his arms.