After his undistinguished career in Rome as a jurist and an orator, he entered the military. His first recorded campaign was under Quintus Servilius Caepio and ended at the Battle of Arausio in 105 BC, where he showed unusual courage. Serving under Gaius Marius, Sertorius succeeded in spying on the wandering Germanic tribes that had defeated Caepio. After this success, he almost certainly fought at the great Battle of Aquae Sextiae (now Aix-en-Provence, France) in 102 BC in which the Teutones and the Ambrones were decisively defeated. He probably also fought at the Battle of Vercellae in 101 BC, where the Cimbri were decisively defeated, ending the German invasion. A few years after the Cimbric wars, Sertorius's patron Gaius Marius fell out of grace for his support of the demagogue Lucius Appuleius Saturninus and he and Sertorius had to get out of Rome for a while. Sertorius travelled to Hispania Ulterior and served its governor, Titus Didius, as a military tribune. He distinguished himself by putting down an insurrection in and around Castulo and was awarded the Grass Crown.