ARIOVISTUS, a German chief who commanded the mixed force of German tribes which entered Gaul at the invitation of the Arverni and Sequani in 71 B.C. After years of warfare he defeated the Aedui at Admetobriga on the middle Rhine in 6r, and re duced them to a client kingdom. His relations with Rome were at first friendly, the Romans apparently not appreciating the danger. By 58 Ariovistus had settled some 120,000 Germans on the left bank of the Rhine; the burden of the invaders was so heavy that in the spring of 58, when Caesar took over the Gal lic provinces, a diet of the tribes of central Gaul decided to ask him for help. Caesar sent a courteous message to Ariovistus ask ing him to return the hostages of the Aedui, and bring no more Germans into Gaul. Ariovistus refused, and hostilities followed the same year. Caesar occupied Vesontio (Besancon), in the territory of the Aedui, and a campaign opened in which he had rather the worse of the preliminary manoeuvring. Ariovistus managed to split Caesar's army and attack one division of it, somewhere near Mulhouse. But a general engagement followed, doubtful at first, which was decided by the Roman reserve under P. Crassus. Ariovistus fled over the Rhine, and is not heard of again. Caesar seems to have left Ariovistus' settlements on the Rhine undisturbed.
See Caesar B.G., I., 31-53. Dio Cas., XXXVIII., 34-50. For the topography of the battle, A von Geller, Caesar's Gallische Krieg, (188o) ; T. R. Holmes, Caesar's Conquest of Gaul (191I) .