DIOCLETIAN, ROMAN EMPEROR

Reigned Nov. 20, 284, to Jan. 5, 305; b. Gaius Aurelius, Dalmatia, c. 245; d. Salona in Dalmatia, Dec. 3, 316. He reorganized the administration of the Empire and inaugurated the last and most severe Roman persecution of Christians. Like many Illyrians, Diocletian was a career soldier who eventually became the comes domesticorum, or commander of the imperial guard. When the Emperor Carus died during the Persian campaign of 283 and his sons were assassinated, the legions supported Diocletian, who subsequently became emperor. The new emperor, gifted with an orderly mind and the equanimity and religious sense of his peasant ancestry, stemmed the anarchy that had racked the Empire for 92 years, and set about restructuring its organization. He instituted stringent measures regarding coinage and price control and strengthened the frontiers, especially against the Persians. In 286 he selected Maximian Hercules as coemperor for the West, and in 293 he associated in the government galerius for the East and Constantius Chlorus for the West as Augusti, or Caesars, with the right of succeeding their respective coemperors. This tetrarchy was given a religious foundation with Diocletian as representative of the god Jupiter and Maximian of Hercules. At first Diocletian tolerated Christianity, particularly since his wife Prisca and his daughter Valeria took an interest in that religion, but once the frontiers of the Empire were secured, he decided to strengthen the ancient pagan religion. He published regulations regarding marriage (295) and an edict against the Manichees (297). That same year he ordered the dismissal from the army of all who would not participate in the pagan rites. By 303 he was convinced that an extermination of Christians was the only certain way of restoring to the Empire internal unity based on religious uniformity. lactantius blames Galerius for this decision (De mortibus persecutorum 11–14), but his judgment is prejudiced. An edict of Feb. 23, 303, ordered the destruction of Christian places of worship, the surrender of Christian books, and the social degradation of Christian office-holders; the second and third edicts directed the imprisonment and execution of clerics who refused to offer sacrifice; and a fourth commanded exile in the mines or death for nonsacrificing Christians. Although in Rome, Spain, and Africa there were martyrs, the Caesar, Constantius Chlorus, seems to have put only the first edict into effect in the northwest; but in the Orient and particularly in Egypt, great numbers of Christians were martyred. On May 1, 305, Diocletian and Maximian retired, whereupon the two Caesars succeeded as coemperors and the persecution died out. In 308 Diocletian attempted to save the tetrarchy whose efficiency was impaired by rivalry between Galerius and Constantius Chlorus. He died in his villa near Salona.

Bibliography: w. ensslin, Paulys Realenzyklopädie der klassischen Altertumswissenschaft, ed. g. wissowa et al. 7A.1:2419–95. w. seston, Dioclétien et la tétrarchie (Paris 1946); Reallexikon für Antike und Christentum, ed. t. klauser [Stuttgart 1941] 3:1036–53. lactantius, De la Mort des persécuteurs, ed. j. moreau (Sources Chrétiennes 39; 1954) 2:231–320.

[e. g. ryan]