Ariovistus maneuvered around Vesontio to cut Caesar's supplies, but Caesar rallied his men, advancing in . According to Caesar, Germanic soothsayers delayed battle until the new moon, though Dio suggests Ariovistus intended to starve the Romans. Whatever the cause, there was widespread panic for a short period among Caesar's military leaders and soldiers due to reports from traders and Gallic auxiliaries about the size and ferocity of the Germanic warriors prepared to face them. However, Caesar was able to assuage their fears and rally his men. Eventually, the Germanic peoples arrayed by tribe—Harudes, Marcomanni, Triboci, Vangiones, Nemetes, Sedusii, Suebi—faced six Roman legions. Caesar notes that his cavalry guard included soldiers from the 10th Legion, who joked they had been "promoted to knights," giving rise to the name ''''. In the ensuing battle, Germanic phalanx tactics briefly pushed back the Romans until Publius Licinius Crassus committed reserves at the critical moment, securing victory. Ariovistus's line of troops broke, fleeing toward the Rhine. Ariovistus escaped, but his wives were killed, one daughter slain, another captured. Caesar's envoys Gaius Valerius Procillus and Marcus Mettius were freed.
Modern analysis The battle between Caesar and Ariovistus has been the subject of extensive scholarly debate. British classical scholar,
Christopher Pelling, claimed that Caesar's descriptions of topography and troop movements are often simplified for his Roman audience, who otherwise lacked precise geographical knowledge. As a result, reconstructions based solely on Caesar's account are problematic and must be treated cautiously. Pelling highlights several key issues. First, Caesar states that after leaving Vesontio he marched for seven days, covering a distance of roughly , before learning of Ariovistus' position. Ariovistus' manoeuvre to cut off Roman supplies also raises questions: Caesar may have omitted mention of unsuccessful cavalry engagements or simplified the geography to make the event more comprehensible. Ancient sources disagree on the distance of the Germanic retreat. Caesar records to the Rhine, while Plutarch and Orosius give . Pelling argues that both readings may be possible: seems too short to emphasize, while may result from later textual corruption. He concludes that Caesar's figure is best regarded as an impressionistic estimate rather than precise measurement. The location of the battlefield also remains uncertain. Scholars have proposed sites at Ribeauvillé, Cernay, and the Mulhouse–Basel plain, but each presents difficulties of distance, terrain, or strategic plausibility. Pelling finds the Belfort region most credible, as it lies naturally on the line of march between Vesontio and Upper Alsace, but even this reconstruction requires assumptions about distances and communications. He concludes that Caesar's simplification of events makes any definitive identification of the battlefield unlikely. ==Aftermath==