<Tr> <Th_colspan="2"> Full name </Th> </Tr> <Tr> <Td_colspan="2"> Diocles (full name unknown) (from birth to accession); Caesar Gaius Aurelius Valerius Diocletianus Augustus (as emperor) </Td> </Tr> <P> Diocletian (/ ˌdaɪ. əˈkliːʃən /; Latin: Gaius Aurelius Valerius Diocletianus Augustus), born Diocles (244--312), was a Roman emperor from 284 to 305 . Born to a family of low status in Dalmatia (Roman province), Diocletian rose through the ranks of the military to become roman cavalry commander to the Emperor Carus . After the deaths of Carus and his son Numerian on campaign in Persia, Diocletian was proclaimed emperor . The title was also claimed by Carus' other surviving son, Carinus, but Diocletian defeated him in the Battle of the Margus . Diocletian's reign stabilized the empire and marks the end of the Crisis of the Third Century . He appointed fellow officer Maximian as Augustus, co-emperor, in 286 . </P> <P> Diocletian delegated further on 1 March 293, appointing Galerius and Constantius as Caesars, junior co-emperors . Under this' tetrarchy', or "rule of four", each emperor would rule over a quarter - division of the empire . Diocletian secured the empire's borders and purged it of all threats to his power . He defeated the Sarmatians and Carpi during several campaigns between 285 and 299, the Alamanni in 288, and usurpers in Egypt between 297 and 298 . Galerius, aided by Diocletian, campaigned successfully against Sassanid Persia, the empire's traditional enemy . In 299 he sacked their capital, Ctesiphon . Diocletian led the subsequent negotiations and achieved a lasting and favorable peace . </P>

The roman general who began a new system of military