The Battle of the Isère River took place near the modern day French town of Valence at the confluence of the Isère and Rhône rivers. Roman consular legions were dispatched into Gaul repeatedly over a time period stretching from 125 to 121 BC to assist allies who repeatedly had come under attack from various Gallic tribes, most prominently the Salluvii, Allobroges, and Arverni. Each year during this time, a newly elected consul was dispatched by the Senate to Cisalpine Gaul in an effort to finally end the threat of these tribes towards the Roman allies in the region, and ultimately, to establish direct Roman control of the area. A major battle was won by Gnaeus Domitius Ahenobarbus at Vindalium, and finally, he, joined by Quintus Fabius Maximus Allobrogicus, defeated a massive combined force of at least 120,000 Allobroges and Arverni at the Isère River.
Background
Up until 125 BC, Roman influence had not yet been expanded into the region of coastline between the Alps and the Pyrenees. That year, however, the Romans were inexorably pulled into conflict in the area as their long-time trading partner and ally, the city of Massilia, was attacked by a Gallic tribe, the Salluvii. The Senate dispatched that year's consul, Marcus Fulvius Flaccus, to deal with the threat that was now menacing the Roman ally. Defeating the Saluvii, Flaccus became the first Roman to defeat any of the Ligurian peoples beyond the Alps, and was awarded a triumph upon his return to Rome in 122 BC. During Flaccus’ time fighting in Gaul, he was accompanied by Gaius Sextius Calvinus, who had been appointed consul for the year of 124 BC. Calvinus, after defeating the Salluvii along with Flaccus, went on to found the colony of Aquae Sextiae, named as such for its proximity to various streams of cold and warm water. The Roman victory was not all-encompassing, however, as Teutomalius, king of the Saluvii, gathered his surviving men and joined with the Allobroges, creating an even larger threat for the burgeoning Roman power in Gaul. Concerned, the Senate again dispatched a consul, this one elected for the year 122 BC, named Gnaeus Domitius Ahenobarbus. This Roman force was sent northwards under the pretext that the Allobroges had received the Roman enemy Teutomalius, and had combined with his remaining forces to attack a Roman ally in the region, a tribe known as the Aedui. It is possible, however, that an alternate motive existed for this maneuver by the Romans, judging by the fact that Ahenobarbus had a clear ambition to construct a road which would link Roman-controlled areas in Gaul and Spain to each other. As Ahenobarbus’ campaign dragged on into 121 BC, he was joined by a newly elected consul for that year, Quintus Fabius Maximus Allobrogicus. This Roman force finally met decisively with the force of Allobroges, remaining Salluvi under Teutomalius, and Arverni under their king Bituitus, at Vindalium on the confluence of the rivers Sulga and Rhône, near modern-day Avignon. The Romans won a huge victory, largely aided by their use of war elephants, the presence of which terrified and scattered many of the Gauls and their horses. Some twenty thousand Allobroges were killed by the Romans there, with a further three thousand being captured.
Battle
The Arverni king Bituitus escaped however, and continued resistance against the victorious Romans. Bituitus again lined up for battle in the autumn of 121 BC against the Romans with a massive army, positioning it at the confluence of the Isère and Rhône rivers near modern-day Valence. Little specifics are known about the ensuing Battle of the Isère River, but it can be assumed that many of the same Roman war elephants which were employed in the previous overwhelming victory at the Battle of Vindalium were used in the same fashion against the Gauls. Fabius, who had sustained an injury shortly before the battle, continued to lead his troops during the fighting, urging his men on while being borne around on a litter. So, despite the Romans being far outnumbered in battle, their victory was complete, and it is said the Bituitus’ army lost some 120,000 men. Appian states that Roman losses numbered only 15 men. The Arverni king was captured in battle by Ahenobarbus, and was shipped back to Rome in anticipation of a triumph to celebrate the massive Roman victory. The significance of the victory was not lost on the proud Ahenobarbus and Fabius, who both erected towers of stone where their victories in the campaign had been won, adorning them with captured arms of the enemy in a gloating display visible to the local Gauls, an upbraiding which, according to Roman historian Florus, was unusual, and showed what the hard-fought victories meant to the Roman commanders.
Aftermath
In commemoration of the victory, Fabius was given the cognomen Allobrogicus, and both he and Ahenobarbus were awarded triumphs in 120 BC. Fabius' triumph in particular was renowned for its splendour, as the captured Arverni king Bituitus was paraded throughout the streets of Rome in the same silver armour which he had worn into battle. To further commemorate his victory, Allobrogicus erected a triumphal arch, at the Via Sacra, between the Regia and the House of the Vestals, the first ever to be constructed in the forum. Atop the arch was erected a sculpture of the victorious consul.
