There was in the Helvetic conglomeration a people renowned for their valor, the Boii; Cæsar permits the Burgundians to receive them into the number of their fellow-citizens, and give them lands at the confluence of the Allier and the Loire. As to the other barbarians, with the exception of 6,000 who had attempted to withdraw from the capitulation by flight, he obliges them to return to their country, dismisses them without ransom, instead of selling them as slaves, and thus drawing from them a considerable profit, according to the general usage of that period.[561] By preventing the Germans from establishing themselves in the countries abandoned by the immigration, he made a calculation of interest secondary to a high political sentiment, and foresaw that Helvetia, by its geographical position, was destined to be a bulwark against invasion from the north, and that, then as now, it was important for the power seated on the Rhone and the Alps to have on its eastern frontiers a friendly and independent people.[562] [Sidenote: Campaign against Ariovistus.] III. The victory gained near Bibracte has, at one blow, restored the prestige of the Roman arms. Cæsar has become the arbitrator of the destinies of a part of Gaul: all the peoples comprised between the Marne, the Rhone, and the mountains of Auvergne, obey him.[563] The Helvetii have returned into their country; the Burgundians have re-conquered their ancient preponderance. The assembly of Celtic Gaul, held with his permission at Bibracte, invokes his protection against Ariovistus, and, to the far north, the people of Trèves hasten to denounce to him a threatened invasion of Germans. It had always been a part of the policy of the Republic to extend its influence by going to the succour of oppressed peoples. Cæsar could not fail to regulate his conduct upon this principle. Not only did it concern him to deliver the Gauls from a foreign yoke, but he sought to deprive the Germans of the possibility of settling on the banks of the Saône, and thus threatening the Roman province, and perhaps Italy itself. Before having recourse to arms, Cæsar, who, during his consulship, had caused Ariovistus to be declared the ally and friend of the Roman republic, undertook to try upon him the means of persuasion. He sent to demand an interview, and received only a haughty reply. Soon, informed that, three days before, the German king has crossed his frontiers at the head of a numerous army, and that, on another side, the hundred cantons of the Suevi are threatening to cross the Rhine towards Mayence, he starts from Tonnerre in haste to go forward to meet him. When he arrives near Arc-en-Barrois, he learns that Ariovistus is marching with all his troops upon Besançon. He then turns to the right, anticipates him, and takes possession of that important place. No doubt, at the news of the march of the Roman army, Ariovistus slackened his own, and halted in the neighbourhood of Colmar.