The reign of emperor Diocletian is one of the important and critical periods in the history of Rome. Henceforth three is too little in common with the Empire of I—II centuries A.D. in it. Principate gave place to Dominate. Just as Augustus had laid the foundation of the State system existing up to a last quarter of III centure A.D., Diocletian, having succeeded in transformation of the decrepit principate and in strengthening of external power of the Empire, created the State system, that lasted until the very fall of Rome and became a base of the State system of Byzantine in the East.
The time, preceding Diocletian's accession to the emperor throne, was extremely difficult for Rome. The Empire had lost its integrity, the external power of the State sharply weakened, powerful social movements constantly shook many provinces. All Gallia was involved with a grandiose revolt of the bagauds. New states was formed on short term. Palmira being a little town and the capital of an insignificant state earlier, turned with amazing speed to a centre of the huge empire, which captured a large part of east provinces of Rome.
The external wars that sharply undermined prestige of the central authorities and scattered the myth about invincibility of roman weapon, had brought hardest defeats to the Romans. In 251 A.D. Roman Army suffered a terrible defeat in a battle with the Goths at Abritte, where emperor Decius was also killed. In 260 A.D. Persian king Shapur had broken the Romans and captured emperor Valerian. For the first time Rome felt such disgrace. The captive emperor was forced to be a servant of the king — winner. Such cruel failures promoted reinforcement of social struggle of oppressed classes and that frightened big land — owners in provinces very much. From the second half of III centure A.D. they being to search for an alliance with Roman government and to rally around of it. The rallying of main forces of the slave — holding class allowed to restore the unity of Roman State.
Emperor Claudius the Second put a shattering defeat to the Goths in the battle at Naissus in 269, Emperor Aurelian (270-275 A.D.) destroyed
the Palmyrian and Gallian empires, Emperor Prob (276-282 A.D.) expelled The Franks from Gaullia and successfully waged on the Moors in Africa.
At the first years ofreign of Diokletian (284-305 A.D.) the integrity of the Empire was finally established. Maximian, the fellow — governer of Diokletian, suppressed the social mivements in Gallia and Nothern Africa, Diokletian himself quelled the revolt in Egypt, the Domination of Rome was restored in Britain. The successful wars with the Persian, the Franks, the Allemmans lifted the foreing — policy authority of Rome impossible to fix these success without complete transformstion of all state organism.
The events of II centure A.D. testified about deep changes in the economic and social life of the Empire. The change of political organization was inevitable. Only amplification of the state authority, based on a powerful army and a remified bureaucratic machinery of the State, could prevent recurrence of the events of middle of III centure A.D.
The task of complite transformation of political organization of the roman society also was carried out by Emperor Diocletian.
First of all Diocletian decided to create a new system of the imperial authority. He established the constant institute of co-governors. At first — diarchy, when the Empire is operated by two emperors one in the east, other on the west, and then — tetrarchy, when together with two senior emperors — Augustus — appear the younger ones — Caesars. With Augustus Diocletian the Caesar was Galerius, with Augustus Maximian — Constantius Chlorus. In the first, and, by the way, in the last time in the history of Rome Diocletian attempted to set up an absolutely precise system of succession to the throne — two Augustus would be replaced by Caesars, which becoming augustus select new caesars for themselves. Also there was established a temporary terminator of government of Augustus — 20 years. The status of the emperor finally changed too. Henceforth the ruler of Rome was not princeps — the first in Senate, but he was dominus now — the Master. Dominus et Deus — Master and Lord — it is an official title of Roman emperors in the epoch of Dominate. For sthrenghtening prestige of the imperial authority Diocletian sets up imperial ceremonial at his court, borrowed it from Sassanian Persia.
Under Diocletian, in connection with establishment of Tetrarchy, the administrative reform of the Empire was conducted too. The extensive territories are fixed for each of the tetrarchies: for Diocletian — Thrakia, Asia Minor, Siria, Mesopotamia, Egypt; for Maximian — Italy, and Nothern Africa; for Galerius — Greece, Macedonia, Illiria;
for Constantius Chlorus — Gallia, Britain and Spain. The number of provinces is doubled — now there are 100 of them. Italy loses its special status, turning on an ordinary area of the Empire. Rome, keeping the status of the capital, loses its role as a residence of the Emperor. The Roman Senate f orteits the status of supreme body of the Empire, turning to a council on administration of Rome-city. The centre of the Empire moves to the east.
Diocletian establishes the new tax system, that sirvived the Rome and was preserved in Byzantine. An attachment farmers to land and citizens to residence becomes its consequence. The finance is reformed the monetary system renovates. However the grandious attempt of Diocletian to set up the rigid state control over prices and incomes of the population had failed. The last great prosecution of the christians finished with the failure too. The Diocletian's favourite child — Tetrarchy — also couldn't survive his reign.
At the same time the political system as a whole, the principal of taxation, the attachement of estates — all of this outlived Diocletian for many centuries.
In 305 A.D., after celebrating the triumph in Rome, where the capture family of Persian king Narses was led through, Diocletian in perfect accordance with his own statute about 20-years term of administrating of Augustus, resigned and forced Maximian to do the same.
He moved off in Salon — city in his native Dalmatia, where he lived up to his decease in 313. He didn't interfere with political business anymore. Galerius and Constantius Chlorus became new Augustus. The Diocletian's position passed to Galerius.
The importance of the Diocletian's state reforms consists, first of all in establishment of the new political system, that was included in the history of Rome under the name of Dominate. The Roman state becomes an unlimited absolute monarchy.
It was the epoch of last revival of former glory of the Roman Army, the occurrence of the new management system and the creation of the new machinery of the State. At the same time Diocletian was last, who tried to keep in inviolability the ancient religion of Rome, fighting with Christianity very cruely. He is the last great oppressor of the christians.
The reign of Diocletian is some kind of critical time, when the new political system was established, but not all elements of the old one was rejected.
The long reformatory activity of Diocletian testifies, that he was a person of outstanding energy, state wit and military talent.