Faced with mounting military problems, in 286 he divided the empire between himself in the east and Maximian in the west. Diocletian synonyms, Diocletian pronunciation, Diocletian translation, English dictionary definition of Diocletian. and died a few years later, disillusioned by the quarrels among his successors. ad 245?-313? ə ˈ k l iː ʃ ən /; Latin: Gaius Aurelius Valerius Diocletianus; born Diocles; 22 December c. 244 – 3 December 311) was a Roman emperor from 284 to 305. (245–313), Roman emperor 284–305; full name Gaius Aurelius Valerius Diocletianus. See more. Diocletian launched the final persecution of the Christians (303). He abdicated in 305 C.E. Originally Gaius Aurelius Valerius Diocletianus. Diocletian definition, Illyrian soldier: emperor of Rome 284–305. Born to a family of low status in Dalmatia, Diocletian rose through the ranks of the military to become a cavalry commander of the Emperor Carus's army. Diocletian divided the empire administratively into a tetrarchy, or four-ruler system. He also divided it into eastern and western regions—a move that some historians believe paved the way for the rise of the Byzantine Empire. Diocletian (/ ˌ d aɪ.