Aurelian became emperor at Sirmium in September 270. Then Aurelian's army overcame Quintillus's army in a battle at Aquileia. (Quintillus was the emperor and the brother of Claudius Gothicus, the previous emperor.) Latin histories (the "Epitome de Caesaribus" and the work of Eutropius) say that Aurelian was emperor for five years and six months. This means that Aurelian may have started a rebellion against Claudius in February or March 270. However, this is not in the Roman histories. The Roman calendar had a festival for the anniversary of Aurelian's accession as emperor. It was on the day that Claudius Gothicus died.