Diocletian in Wikipedia
Gaius Aurelius Valerius Diocletianus[notes 1] (c. 22
December 244 – 3 December 311), commonly known as
Diocletian, was a Roman Emperor from 284 to 305.
Born to an Illyrian family of low status in the Roman
province of Dalmatia, Diocletian rose through the ranks of
the military to become cavalry commander to the emperor
Carus. After the deaths of Carus and his son Numerian on
campaign in Persia, Diocletian was acclaimed emperor. The
title was also claimed by Carus' other surviving son,
Carinus, but Diocletian defeated him in the Battle of the
Margus. With his accession to power, Diocletian ended the
Crisis of the Third Century. He appointed fellow-officer
Maximian Augustus, his senior co-emperor, in 285. He
delegated further on 1 March 293, appointing Galerius and
Constantius as Caesars, junior co-emperors. Under this
"Tetrarchy", or "rule of four", each emperor would rule over
a quarter-division of the empire. Diocletian secured the
empire's borders and purged it of all threats to his power.
He defeated the Sarmatians and Carpi during several
campaigns between 285 and 299, the Alamanni in 288, and
usurpers in Egypt between 297 and 298. Galerius, aided by
Diocletian, campaigned successfully against Sassanid Persia,
the empire's traditional enemy. In 299 he sacked their
capital Ctesiphon - Diocletian led the subsequent
negotiations and achieved a lasting and favorable peace.
Diocletian separated and enlarged the empire's civil and
military services and reorganised the empire's provincial
divisions, establishing the largest and most bureaucratic
government in the history of the empire. He established new
administrative centers in Nicomedia, Mediolanum, Antioch,
and Trier, closer to the empire's frontiers than the
traditional capital at Rome had been. Building on third-
century trends towards absolutism, he styled himself an
autocrat, elevating himself above the empire's masses with
imposing forms of court ceremonial and architecture.
Bureaucratic and military growth, constant campaigning, and
construction projects increased the state's expenditures and
necessitated a comprehensive tax reform. From at least 297
on, imperial taxation was standardized, made more equitable,
and levied at generally higher rates...