Battle of Magetobriga The Battle of Magetobriga ( Amagetobria , Magetobria , Mageto ' Bria , Admageto ' Bria ) was fought in 63 BC between rival tribes in Gaul . The Aedui tribe was defeated and massacred by the combined forces of the Sequani and Arverni tribes , who had enlisted the aid of the German Suebi tribe under the Germanic king Ariovistus . Following their defeat , the Aedui sent envoys to the Roman Senate , their traditional ally , for aid . The Roman general Julius Caesar would subsequently use their request for aid as a basis for entering central Gaul from his province in southern or Mediterranean Gaul . Background . According to Strabo , the cause of the conflict was commercial . The Arar ( Saône ) River formed part of the border between the Haedui and their hereditary rivals , the Sequani . Each tribe claimed the Arar and the tolls on trade along it . The Sequani controlled access to the Rhine River and had built an oppidum ( a fortified town ) at Vesontio to protect their interests . The Battle . In 63 BC the Sequani and Arverni secured the aid of Ariovistus , a king of the Germanic Suebi tribe , to settle the hereditary dispute . Ariovistus crossed the Rhine with a confederation of Germanic tribes . The Battle of Magetobriga , the final battle between the Aedui and their enemies , took place close to the Sequani town of Magetobria ( or Amagetobria ) ( now known as Amage 10 km from Luxeuil ) . Ariovistus ' 15 , 000 Germanic tribesmen turned the tide , and the Aedui became tributary to the Sequani . In return , Ariovistus was promised land grants in Gaul , although exactly where is not certain . In 63 BC , following the Aedui ' s defeat at Magetobriga , the Aedui druid Diviciacus travelled to Rome and spoke before the Roman senate to ask for military aid . While in Rome , Diviciacus was a guest of Cicero , who spoke of his knowledge of divination , astronomy and natural philosophy , and names him as a druid . Cicero writes in 60 BC of a defeat sustained by the Haedui , perhaps in reference to Magetobriga . [ I ] n public affairs for the moment the chief subject of interest is the disturbance in Gaul . For the Haedui — " our brethren " — have recently fought a losing battle , and the Helvetii are undoubtedly in arms and making raids upon our province . The senate has decreed that the two Consuls should draw lots for the Gauls , that a levy should be held , all exemptions from service be suspended , and legates with full powers be sent to visit the states in Gaul , and see that they do not join the Helvetii . Subsequent events . Ariovistus Stays in Gaul . In the wake of victory , and to the dismay of his ' allies ' , Ariovistus stayed in Gaul . According to Caesar , he seized a third of the Aeduan territory and proceeded to settle 120 , 000 Germani there as the nucleus of a new Germanic kingdom . Caesar writes : " But a worse thing had befallen the victorious Sequani than the vanquished Aedui , for Ariovistus , a king of the Germani , had settled in their territories , and had seized upon a third of their land , which was the best in the whole of Gaul , and was now ordering them to depart from another third part , because a few months previously 24 , 000 men of the Harudes had come to him , for whom room and settlements must be provided . " ( " Commentaries on the Gallic War " , I . 31 ) To avoid infringing on his allies , at least for the moment , Ariovistus must have passed over the low divide between the Rhine and the Doubs in the vicinity of Belfort and than have approached the Aedui along the Ognon river valley . That move left the Sequani between him and the Jura mountains , not a tolerable situation for either if they were not going to be allies . Ariovistus made the decision to clear out the Sequani from the strategic Doubs valley and re - populate it with Germanic settlers . He demanded a further third of Celtic land for his allies the Harudes . Caesar makes it clear that Germanic tribes were actually in the land of the Sequani and were terrorizing them . They are said to control all the oppida , but this statement is not entirely true , as Vesontio was not under Germanic control . Presumably , the country to the north of there was under Germanic control . Caesar ' s Intervention . Following Caesar ’ s victory over the Helvetii , the majority of the Gallic tribes congratulated Caesar and sought to meet with him in a general assembly . Diviciacus , a head of the Aeduan government and spokesmen for the Gallic delegation , expressed concern over Ariovistus ’ conquests and the hostages he had taken . Ariovistus ' demand that the Sequani give him more land to accommodate the Harudes people , ' concerned ' Rome because , if the Sequani conceded , Ariovistus would be in a position to take all of the Sequani land and attack the rest of Gaul . The Gallic request afforded Caesar the perfect pretext to expand his intervention as " the savior and not the conqueror of Gaul , " . Caesar would defeat Ariovistus at the Battle of Vosges . In the following battle against Caesar near Vesontio ( Besançon ) , the Harudes formed one of the seven tribal divisions of Ariovistus ' host . After suffering a crushing defeat at the hands of the Romans , the Germani fled back over the Rhine . Caesar would eventually subjugate the whole of Gaul .