The attack of Flaccus, however, fell in the first instance not on the Arverni, but on the smaller tribes in the district between the Alps and the Rhone, where the original Ligurian inhabitants had become mixed with subsequent arrivals of Celtic bands, and there had arisen a Celto-Ligurian population that may in this respect be compared to the Celtiberian. He fought (629, 630) with success against the Salyes or Salluvii in the region of Aix and in the valley of the Durance, and against their northern neighbours the Vocontii (in the departments of Vaucluse and Drome); and so did his successor Gaius Sextius Calvinus (631, 632) against the Allobroges, a powerful Celtic clan in the rich valley of the Isere, which had come at the request of the fugitive king of the Salyes, Tutomotulus, to help him to reconquer his land, but was defeated in the district of Aix. When the Allobroges nevertheless refused to surrender the king of the Salyes, Gnaeus Domitius Ahenobarbus, the successor of Calvinus, penetrated into their own territory (632). Up to this period the leading Celtic tribe had been spectators of the encroachments of their Italian neighbours; the Arvernian king Betuitus, son of the Luerius already mentioned, seemed not much inclined to enter on a dangerous war for the sake of the loose relation of clientship in which the eastern cantons might stand to him. But when the Romans showed signs of attacking the Allobroges in their own territory, he offered his mediation, the rejection of which was followed by his taking the field with all his forces to help the Allobroges; whereas the Haedui embraced the side of the Romans. On receiving accounts of the rising of the Arverni, the Romans sent the consul of 633, Quintus Fabius Maximus, to meet in concert with Ahenobarbus the impending attack. On the southern border of the canton of the Allobroges at the confluence of the Isere with the Rhone, on the 8th of August 633, the battle was fought which decided the mastery of southern Gaul. King Betuitus, when he saw the innumerable hosts of the dependent clans marching over to him on the bridge of boats thrown across the Rhone and the Romans who had not a third of their numbers forming in array against them, is said to have exclaimed that there were not enough of the latter to satisfy the dogs of the Celtic army. Nevertheless Maximus, a grandson of the victor of Pydna, achieved a decisive victory, which, as the bridge of boats broke down under the mass of the fugitives, ended in the destruction of the greater part of the Arvernian army. The Allobroges, to whom the king of the Arverni declared himself unable to render further assistance, and whom he advised to make their peace with Maximus, submitted to the consul; whereupon the latter, thenceforth called Allobrogicus, returned to Italy and left to Ahenobarbus the no longer distant termination of the Arvernian war. Ahenobarbus, personally exasperated at king Betuitus because he had induced the Allobroges