Also found in: Dictionary, Thesaurus, Wikipedia.


(Caius Aurelius Valerius Diocletianus) (dī`əklē`shən), 245–313, Roman emperor (284–305), b. near Salona, Dalmatia (the modern Split, Croatia). Of humble birth, he obtained high military command under Probus and Aurelian and fought under Carus in Persia. The army proclaimed him emperor after the death of Numerian, and he became sole ruler when CarinusCarinus
(Marcus Aurelius Carinus) , d. 285, Roman emperor (283–85). He was the son of Carus, who left Carinus as ruler in the West when he went to the East on a campaign against the Parthians.
..... Click the link for more information.
, joint emperor with Numerian, was murdered by his own officers. In order to repel the Germans he appointed MaximianMaximian
(Marcus Aurelius Valerius Maximianus) , d. 310, Roman emperor, with Diocletian (286–305). An able commander, he was made caesar (subemperor) by Diocletian in 285 and augustus in 286.
..... Click the link for more information.
 augustus (286) and Constantius IConstantius I
(Constantius Chlorus) , c.250–306, Roman emperor (305–6). A career general, he gave up Helena to marry Theodora, the daughter of Maximian. He was made caesar (subemperor) under Maximian in 293 and gained prestige when his forces defeated the rebel
..... Click the link for more information.
 and GaleriusGalerius
(Caius Galerius Valerius Maximinianus) , d. 310, Roman emperor (305–10). Diocletian appointed him caesar for the eastern part of the empire in 293 (Constantius I was caesar of the West). He had to conduct hard campaigns in Pannonia and Asia.
..... Click the link for more information.
 caesars (293). The four rulers had their respective capitals at Nicomedia, Mediolanum (modern Milan), Treveri (modern Trier), and Sirmium. In Diocletian's reign Britain was restored (296) to the empire, the Persians were subjugated (298), and the Marcomanni were expelled from the empire. Diocletian was the first to divide the empire formally and to set up a genuine autocracy with no theoretical checks. The Roman senate became a municipal council and all vestiges of Republican institutions disappeared. His economic reforms included an attempt to restore the gold standard and the Edict of Diocletian (301), an economic measure to regulate prices and wages. Its effects, however, proved ruinous to agriculture and the markets. The persecution of the Christians in the latter part of his reign was a course to which he had been instigated by Galerius. Diocletian abdicated (305), and Maximian resigned at the same time. Diocletian retired to his castle at Salona, from which he saw his system fail as his successors began to quarrel among themselves.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(Gaius Aurelius Valerius Diocletianus). Born 243 A.D., in Dioclea; died between 313 and 316 A.D., in Salonae, Dalmatia. Roman .emperor from 284 to 305.

Diocletian was the son of a freedman and began his army service as a foot soldier. He advanced during the reign of Emperor Probus and became governor of the province of Moesia. During the reign of Emperor Numerian, Diocletian commanded his bodyguard, and after Numerian’s death he was proclaimed emperor. Linked with Diocletian’s name is the establishment of the Dominate—a type of monarchy akin to ancient Eastern despotism. In order to overcome a sociopolitical and economic crisis at the end of the third century. Diocletian carried out reforms that temporarily stabilized the position of the empire. To strengthen the central authority, Diocletian appointed Maximian as his coruler in 286 and designated him as a second Augustus. In 293 he divided the empire into four parts (the tetrarchy), after providing the Augusti with the aid of two junior corulers, Gaius Galerius and Constantius Chlorus, as Caesars. The entire empire was divided into 12 dioceses, which encompassed 101 or 120 redistricted provinces. Rome remained the capital, but the residences of the rulers were located concurrently in Nicomedia (Diocletian), Sirmium (Galerius), Mediolanum (Maximian), and Treviri (Constantius Chlorus).

Diocletian reinforced the army, increasing its numerical strength to 450,000 men by means of conscription. Some legions were stationed permanently in certain border areas, while others were transferred here and there as required. Diocletian regularized taxation, establishing a direct land and capitation tax in kind, which reflected the shift toward subsistence farming in the economy. He also attempted to bring some order into finances by minting full-valued coins. He also fought against speculation by issuing an edict on prices in 301. Diocletian extended the power of the landowning magnates over the dependent population, but at the same time he made them responsible for collecting taxes and supplying recruits; he issued a number of edicts in favor of small and medium landowners, providing, in particular, for the dissolution of contracts for the sale of lands that had previously been sold at unfairly low prices.

Diocletian harshly suppressed uprisings of the masses and separatist movements in the provinces as follows: in 285-286, the Bagaudae in Gaul; in 290, the Mauritanian tribes in Africa; in 294-295, the usurper Achilleus in Egypt; and in 297, the usurper Carausius in Britain. Diocletian and his corulers repulsed invasions by the tribes of Carpi and lazyges on the Danube and the Franks and Alamanni on the Rhine; they waged successful campaigns against the Persians (in 286-287 and in 296-298), as the result of which the Romans strengthened their influence in Armenia and Hiberia and seized part of Mesopotamia. In 303-304, Diocletian undertook persecutions of the Christians. He abdicated jointly with Maximian in 305 and spent his last years on his estate in Salonae (present-day Split).


Novitskaia, K. I. “Nekotorye voprosy agrarnoi politiki nachala Dominata.” Vestnik drevnei istorii, 1961, no. 4.
Arkhangel’skii, S. I. Ukaz Diokletiana o taksakh. Nizhny Novgorod, 1928.
Seston, W. Diocletien et la tétrarchie. Paris, 1946.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


Roman emperor (284–305); instituted general persecutions of Christians. [Rom. Hist.: EB, 5: 805–807]
See: Cruelty
Allusions—Cultural, Literary, Biblical, and Historical: A Thematic Dictionary. Copyright 2008 The Gale Group, Inc. All rights reserved.


full name Gaius Aurelius Valerius Diocletianus. 245--313 ad, Roman emperor (284--305), who divided the empire into four administrative units (293) and instigated the last severe persecution of the Christians (303)
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Saint George refused to give up his faith, and although Diocletian tried to convert him with promises of wealth and prosperity he refused.
Passing through Diocletian's Palace, it's clear to see the impact the show has had on tourism here - shops are filled with merchandise from the fantasy saga, and a number of the walking tours feature filming locations.
Then emperor Diocletian knew that it was Mark's daughter, Saint Demiana, who convinced her father to once again worship Jesus.
Diocletian initially tried to convert him with offers of wealth and land, but when he refused, he was beheaded on April 23, 303.
For nearly all of his reign, Diocletian, although a pagan, was tolerant of Christians, allowing several to occupy important positions of trust within the imperial court and in his personal household.
Diocletian's Palace seems to have been completed by the year 305, in time for the emperor to retire from public life.
Split, with the remains of Diocletian's palace at its heart, and a bustling market just outside the walls, is in many ways more interesting than overcrowded Dubrovnik.
In AD 298 Diocletian withdrew the Roman troops from the Dodecaschoenos--according to Procopius (De bellis 1.19.27-37) making a treaty with the Nobadai and the Blemmyes.
A huge pyramid had been discovered off the Azores islands by Portuguese amateur sailor Diocletian Silva.
The second section of the book goes back to the third century AD and the difficulties besetting Emperor Diocletian. The child of one of his aides, Gerontius of Cappadocia, was born and named George.
He drew up the new system in part to distance it from the calendar in use at the time, which was based on the years since the reign of the Roman emperor Diocletian.