245-313. Roman emperor 284-305. A Dalmatian of low birth, originally named Diocles, he rose to be commander of Emperor Numerian's bodyguard, and later the Augustus after defeating Numerian's brother, Carinus. In 293 he established his famous tetrarchy. Galerius was his Caesar in the East, while Maximian and Constantius Cholorus were in the West. His genius was as an organizer, and many of his administrative measures lasted for centuries. He believed that the old Roman religion, tradition, and discipline would help to reinforce imperial unity. This policy formed the background to the persecution of Christians undertaken in 303, possibly at the insistence of Galerius. Four edicts were issued before Diocletian's abdication in 305, and they were enforced with varying degrees of severity, most harshly in Palestine and Egypt. The first edict required the destruction of churches and books, the next two were aimed at the clergy, and the fourth included both laity and clergy.