 Diocletian divided the Empire again in 293 AD , appointing two Caesars ( junior emperors ) to rule over further subdivisions of East and West . Each would be subordinate to their respective Augustus ( senior emperor ) but would act with supreme authority in his assigned lands . This system would later be called the Tetrarchy . Diocletian 's first appointee for the office of Caesar was Constantius ; his second was Galerius , a native of Felix Romuliana . According to Lactantius , Galerius was a brutal , animalistic man . Although he shared the paganism of Rome 's aristocracy , he seemed to them an alien figure , a semi @-@ barbarian . On 1 March , Constantius was promoted to the office of Caesar , and dispatched to Gaul to fight the rebels Carausius and Allectus . In spite of meritocratic overtones , the Tetrarchy retained vestiges of hereditary privilege , and Constantine became the prime candidate for future appointment as Caesar as soon as his father took the position . Constantine went to the court of Diocletian , where he lived as his father 's heir presumptive . 
