"Diocletian (/ˌdaɪ.əˈkliːʃən/; Latin: Gaius Aurelius Valerius Diocletianus Augustus), born Diocles (22 December 244 – 3 December 311), was a Roman emperor from 284 to 305. Born to a family of low status in Dalmatia, 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´ 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. Diocletian reigned in the Eastern Empire, and Maximian reigned in the Western Empire. Diocletian delegated further on 1 March 293, appointing Galerius and Constantius as Caesars, junior co-emperors, under himself and Maximian respectively. 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 favourable peace." - (en.wikipedia.org 30.10.2019)
