Diocletian was not the only challenger to Carinus ' rule: the usurper M. Aurelius Julianus, Carinus ' corrector Venetiae, took control of northern Italy and Pannonia after Diocletian's accession.

In spite of his failures, Diocletian's reforms fundamentally changed the structure of Roman imperial government and helped stabilize the Empire economically and militarily, enabling the Empire to remain essentially intact for another hundred years despite having seemed near the brink of collapse in Diocletian's youth.

Constantine's rule, however, validated Diocletian's achievements and the autocratic principle he represented: the borders remained secure, in spite of Constantine's large expenditure of forces during his civil wars ; the bureaucratic transformation of Roman government was completed ; and Constantine took Diocletian's court ceremonies and made them even more extravagant.

From the Emperor Diocletian's tetrarchy ( c. 300 ) they became the administrators of the four Praetorian prefectures, the government level above the ( newly created ) dioceses and ( multiplied ) provinces.

When the proposed government of universal Christendom by five patriarchal sees ( Rome, Constantinople, Alexandria, Antioch and Jerusalem, known as the pentarchy ), under the auspices of a single universal empire, was formulated in the legislation of Emperor Justinian I ( 527-565 ), especially in his Novella 131, and received formal ecclesiastical sanction at the Council in Trullo ( 692 ), the name " patriarch " became the official one for the Bishops of these sees, and the title " Exarch " remained the proper style of the metropolitans who ruled over the three remaining ( political ) dioceses of Diocletian's division of the Eastern Prefecture, namely the Exarchs of Asia ( at Ephesus ), of Cappadocia and Pontus ( at Caesarea ), and of Thrace ( at Heraclea Sintica ).

Diocletian's preference for activist government, combined with his self-image as a restorer of past Roman glory, presaged the most pervasive persecution in Roman history.

The Diocletianic regime's activist stance, however, and Diocletian's belief in the power of central government to effect major change in morals and society made him unusual.

Diocletian's reduction of the Praetorian Guards to the level of a simple city garrison for Rome lessened the military powers of the prefect, but the office retained much civil authority.

Gaining sole reign of the empire, he is also noted for re-establishing a single imperial capital, choosing the site of ancient Byzantium in 330 ( over of the current capitals, which had effectively been changed by Diocletian's reforms to Milan in the West, and Nicomedia in the East ) to build the city soon called Nova Roma ( New Rome ); it was later renamed Constantinople in his honor.

The project was originally commissioned by Maximian upon his return to Rome in the autumn of 298 AD and was continued after his and Diocletian's abdication under Constantius, father of Constantine.

* Maxima of Rome, early Christian saint and martyr killed in Emperor Diocletian's purges

He seems not to have served in any important military or administrative position during Diocletian's and his father's reign, though.

Hébrard was involved in several other major projects, such as the upgrading of Casablanca, reconstruction of Diocletian's palace at Split, and planning for several towns in French Indochina.

Diocletian's reply: " If you could show the cabbage that I planted with my own hands to your emperor, he definitely wouldn't dare suggest that I replace the peace and happiness of this place with the storms of a never-satisfied greed.

Since Diocletian's Tetrarchy ( 296 ), it was the major province of a diocese confusingly called Galliae (' the Gaul s '), to which further only the Helvetic, Belgian ( both also Celtic ) and German provinces belonged ; with the dioceses of Viennensis ( the southern provinces of Gaul ), Britanniae ( also Celtic ) and Hispaniae ( the whole Celtiberian peninsula ) this formed the praetorian prefecture also called Galliae, subordinate to the western emperor.

He probably participated in the Mesopotamian campaign of Carus in 283 and attended Diocletian's election as emperor on November 20, 284 at Nicomedia.

The Christian rhetor Lactantius suggested that Maximian shared Diocletian's basic attitudes but was less puritanical in his tastes, and took advantage of the sensual opportunities his position as emperor offered.

Since emperor Diocletian's Tetrarchy reform ( 293 ), the country was further divided in three provinces, as the small, easternmost region Sitifensis was split off from Mauretania Caesariensis.

Painting depicts two Christian women extracting arrows from St. Sebastian, who has been left for dead by the Roman emperor Diocletian's archers ( between 1851 and 1873 ).

Saint Sebastian ( died c. 288 ) was an early Christian saint and martyr, who is said to have been killed during the Roman emperor Diocletian's persecution of Christians.

Near the city emperor Diocletian, born in Salona, built the Diocletian's Palace ( around year 300 AD ), which is the largest and most important monument of late antique architecture in the World.

Diocletian's Palace (, ) is a building in Split, Croatia, that was built by the Roman emperor Diocletian at the turn of the fourth century AD.

* Both the notion of " partnership " in the form of a senior emperor and several junior co-emperors ( usually, but not necessarily, his sons ), and Diocletian's titulature, but mainly versed in Greek ( e. g. Sebastos for Augustus, a literal translation ), became quite common is the Eastern Roman Empire, i. e. Byzantium, which lasted a further millennium after the fall of the Western Empire.

Some church buildings were specifically built as church assemblies, such as that opposite the emperor Diocletian's palace in Nicomedia.

A Western Roman Empire existed intermittently in several periods between the 3rd and 5th centuries, after Diocletian's Tetrarchy and the reunifications associated with Constantine the Great and Julian the Apostate ( 324 – 363 ).

The rate of pay of the scribes in Diocletian's reign was fixed by his edict de pretiis rerum venalium at 25 denarii for 100 στιχοι in writing of the first quality, and at 20 denarii for the second quality ; what the difference was between the two qualities does not appear.

Following Diocletian's abdication in 305, civil war erupted among the various co-emperors, during which time each of the contenders appointed his own prefect, a pattern carried on during the period where the Empire was shared between Licinius and Constantine I.

One quarter of all inscriptions referring to temple repairs in North Africa between 276 and 295 date to Diocletian's reign.

The dissemination of imperial law to the provinces was facilitated under Diocletian's reign, because Diocletian's reform of the Empire's provincial structure meant that there were now a greater number of governors ( praesides ) ruling over smaller regions and smaller populations.

Diocletian's expansion of the army and civil service meant that the Empire's tax burden grew.

Diocletian's policy of preserving a stable silver coinage was abandoned, and the gold solidus became the Empire's primary currency instead.

Diocletian's reforms shifted the governors ' main function to that of the presiding official in the lower courts: whereas in the early Empire military and judicial functions were the function of governor, and procurators had supervised taxation ; under the new system vicarii and governors were responsible for justice and taxation, and a new class of duces (" dukes "), acting independently of the civil service, had military command.

In the 6th Century, when Justinian increasingly reversed Diocletian's strict separation of civil and military authority, praeses granted military authority over their province were generally elevated to the related, older term Praetor.

Alternatively, a more idiomatic style may develop into an equally prestigious tradition of titles, because of the shining example of the original – thus various styles of Emperors trace back to the Roman Imperator ( strictly speaking a republican military honorific ), the family surname Caesar ( turned into an imperial title since Diocletian's Tetrarchy ).

Diocletian's reign stabilized the Empire and marks the end of the Crisis of the Third Century.

Not all of Diocletian's plans were successful: the Edict on Maximum Prices ( 301 ), his attempt to curb inflation via price controls, was counterproductive and quickly ignored.

Although effective while he ruled, Diocletian's Tetrarchic system collapsed after his abdication under the competing dynastic claims of Maxentius and Constantine, sons of Maximian and Constantius respectively.

It is possible that Flavius Constantius, the governor of Dalmatia and Diocletian's associate in the household guard, had already defected to Diocletian in the early spring.

Following Diocletian's victory, both the western and the eastern armies acclaimed him Augustus.

Diocletian's stay in the East saw diplomatic success in the conflict with Persia: in 287, Bahram II granted him precious gifts, declared open friendship with the Empire, and invited Diocletian to visit him.

It has been surmised that the ceremonies were arranged to demonstrate Diocletian's continuing support for his faltering colleague.

In the spring of 293, in either Philippopolis ( Plovdiv, Bulgaria ) or Sirmium, Diocletian would do the same for Galerius, husband to Diocletian's daughter Valeria, and perhaps Diocletian's praetorian prefect.

In preparation for their future roles, Constantine and Maxentius were taken to Diocletian's court in Nicomedia.

Diocletian's attempts to bring the Egyptian tax system in line with Imperial standards stirred discontent, and a revolt swept the region after Galerius ' departure.

Alexandria, whose defense was organized under Diocletian's former corrector Aurelius Achilleus, held out until a later date, probably March 298.

Bureaucratic affairs were completed during Diocletian's stay: a census took place, and Alexandria, in punishment for its rebellion, lost the ability to mint independently.

Diocletian's reforms in the region, combined with those of Septimus Severus, brought Egyptian administrative practices much closer to Roman standards.

Antioch was Diocletian's primary residence from 299 to 302, while Galerius swapped places with his Augustus on the Middle and Lower Danube.

The next day, Diocletian's first " Edict against the Christians " was published.

Diocletian was demonized by his Christian successors: Lactantius intimated that Diocletian's ascendancy heralded the apocalypse, and in Serbian mythology, Diocletian is remembered as Dukljan, the adversary of God.

Maximian, according to these accounts, swore to uphold Diocletian's plan in a ceremony in the Temple of Jupiter.

Rumors alleging that Diocletian's death was merely being kept secret until Galerius could come to assume power spread through the city.

Maximin appeared and took Diocletian's robes.