Diocletian was the emperor of Rome in the period between November 20, 284 and May 1, 305. He managed to rise in position and later became cavalry commander under the rule of Carus. When the Latter died, his potential successor, Numerian, who also happened to be his son, was to become the Roman Emperor but died during a campaign in Persia.

The two deaths lead to Diocletian becoming the Roman emperor. After deafeating the second son of Carus, by the name Carinus, Diocletian eliminated the only barrier on his way to becoming emperor. After taking over the throne in Rome, he appointed Maximian his Augustus, thus making him his right hand in ruling the empire. The event took place in 285.  

Diocletian was born in Salona. His parents called him Diocles or Diocles Valerius.

The Rise to Power of Diocletian

 
His Dalmatian family was the one with a low status. The first forty years of Diocletian's life are hard to define. It is believed that he was the commander of Roman armed forces on the lower Danube. Some sources state that Diocletian served in Gaul.

In 282 Carus was assigned as emperor by the legions of the upper Danube. Before that Carus was the praetorian prefect. After taking over the throne, Carus started a revolt against the government of emperor Probus and his army, which resigned from confronting the army of Carus and assassinated their leader. Shortly after that Diocletian managed to become a trusted commander of Carus, who then  assigned Diocletian the Count of the Domestics.

Carus died during his campaign against the Persian. The event took place in 284. It is believed that the emperor was stroken by a thurderbolt. The successors of Carus were his two young sons. One of them was Numerian, who controlled the east and the other one was Carinus, who managed the west. After the death of Numerian Diocletian replaces him. Shortly after that Carinus dies. Thus Diocletian started ruling the entire empire.

When taking over the rule of empire the main thing Diocletian had to fix was the barbaric Roman army. Some additonal issues included reistalling the security at the empire's boarders, inmproving the economy and establishing a strong and effetive government.

To establish a firm rule, Diocletian parted the empire into provices, which were fifty. Then the provinces were divided among 12 "dioceses", and these were under a "vicar," which was among 4 "prefectures," each one of the prefectures was under a "praetorian prefect."

Maximianus "Caesar" became his lieutenant in 285. He controled the western half of the Roman Empire.

In 293 Diocletian named two new Caesars, one of them being Constantinus, and the other one was Galerius. The former was assigned to control Gaul and Britain in the west and the latter took the Balkans in the east.

During his early years the emperor was able to defeat Alamanni, Sarmatians, Saracens, Franks, and Persians. In addition, Diocletian was able to suppress rebellions in Britain and Egypt.

Reforms

Diocletian centralized the political authority. He developed policies, in which he put into effect an imperial system of values on different provincial people. Together with his Caesars, Diocletian was considered the restorer of the entire world. His team was believed to gain victory over barbarians, thus securing their world.  

Roman coins critically depreciated. There was very little gold and silver in the empire for restoring a stable currency.

The "Maximum Price Edict" was struck in 301. It meant to limit the level of inflation but it only drove goods onto the black market. Diocletian accepted the fact of money economy failure. He changed the tax system so ordinary citizens and soldiers were paid in kind.

Diocletian restricted the admission of senators into governmental posts that ranked high, this especially concerned military posts. A unifying tool for Diocletian was state religion. Being inspired by Caesar Galerius, he in 303 introduced a series of 4 highly severe rules meant to force Christians to participate in the imperial cult. This started the "Great Persecution."

Diocletian was the emperor of Rome for 20 years. He resigned from the rank on May 1, 305. He ruled the emperorship for twenty years. Maximianus did the same thing. Both Constantius and Galerius became Augusti and Maximinus (305-313) along with Severus (305- 307) became new Caesars of the east and west respectively.

After the resignation Diocletian lived three more years. He was the witness of collapse of the tetrarchy. His successors proved to be selfish, fighting for the power after Diocletian's leave. He saw how statues and portraits of his preceding emperor in his palace torn down damaged and destroyed. Being seriously ill, it is believed that Diocletian committed suicide and died on December 3, 311.