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Diocletian

Augustus of the Eastern Roman Empire (244-311)

28 dated entries naming Diocletian, drawn from 27 separate years between 244 CE and 315 CE. Nothing here is written by us: each line is the sentence a Wikipedia year article used, and the link beside it opens the exact revision.

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3rd century

  • 244December 22 – Diocletian, Roman emperor (d. 311)source
  • 247Prisca, Roman empress and wife of Diocletian (d. 315)source
  • 283The officer Diocles, the future Emperor Diocletian, distinguishes himself in the war against the Persians.source
  • 284November 17 – Diocletian becomes emperor of Romesource
  • 284November 20 – The commander of Numerian's domestici (household troops), Diocles, is chosen to be the new emperor. In a military assembly outside Nicomedia (modern İzmit, Turkey), Diocles claims that the praetorian prefect (and rival for the throne) Arrius Aper murdered Numerian, and he personally stabs and kills the prefect on the spot. The new emperor changes his name to the Latinised 'Diocletian'. Building on existing trends, Diocletian presents his rule as that of a god-like dominus or autocrat.source
  • 285Summer – Battle of the Margus: Emperor Diocletian defeats the forces of Carinus in the valley of the Margus (Serbia). Numerous soldiers desert Carinus during the battle. Carinus then flees to the Pannonian fort of Cornacum, but he is soon slain by his officers.source
  • 286Emperor Diocletian campaigns successfully against Sarmatian raids. The future emperor Constantius defeats the 'Bosporian Sarmatians'.source
  • 288Emperor Diocletian launches a campaign into Germanic territory from the province of Raetia (Switzerland).source
  • 289In this or the following year, Emperor Diocletian campaigns with success against the Sarmatians. The future emperor Galerius may have distinguished himself during this campaign.source
  • 290Emperor Diocletian campaigns with success against Arabic enemies.source
  • 291Winter: The emperors Diocletian and Maximian convene in Milan.source
  • 292The jurist Gregorius, at the court of Emperor Diocletian, produces the Gregorian Code, the first codification of Roman law (approximate date).source
  • 293March 1 – Emperors Diocletian and Maximian appoint Constantius I and Galerius as Caesars. This is considered the beginning of the Tetrarchy, known as the Quattuor Principes Mundi ("Four Rulers of the World"). (Some sources and scholars date Galerius' elevation to May 21.)source
  • 295Emperor Diocletian defeats the Carpi.source
  • 297Emperor Diocletian introduces a new tax system and other economic reforms.source
  • 298Spring: Emperor Diocletian retakes Alexandria and crushes the usurpation of Aurelius Achilleus.source
  • 299Peace of Nisibis: Emperor Diocletian signs a treaty with the Persian king Narseh that will last for 40 years. The Persians accept Roman dominion over Armenia, the Caucasus, and Upper Mesopotamia. The pro-Roman ruler Tiridates III receives all of Armenia as far as the border with Atropatene. Mirian III of the Kingdom of Iberia is made a Roman client, and at some point in time, as a result of the treaty, Caucasian Albania will follow suit. Rome also gains five satrapies beyond the Tigris, which are perhaps given to Tiridates to administer.source
  • 300Emperor Diocletian begins construction of a palace that will become the city of Split (approximate date). Diocletian, who plans on abdicating, intends to use this palace as his place of retirement.source

4th century

  • 301September: Emperor Diocletian issues a reform that revalues the Roman currency.source
  • 302Emperor Diocletian persecutes the Manichaeans, accusing them of being a Persian fifth column.source
  • 304Caesar Galerius, perhaps accompanied by Emperor Diocletian, wins his fourth and final victory over the Carpi. Many of the surviving Carpi and Bastarnae are resettled in the Roman Empire, where they are split up. The Bastarnae are not attested after this time, and the Carpi are attested only once more in the 310s.source
  • 305May 1 – Emperor Diocletian abdicates and retires to his palace at Salona (modern Split) on the Adriatic coast, after a reign of nearly 21 years, in which the last vestiges of republican government have disappeared.source
  • 306Building on the efforts of Diocletian, Galerius introduces the poll tax to central and southern Italy and truncates the size of the Praetorian Guard, with plans to disband the Guard altogether.source
  • 307Near the end of the year, Galerius gives his wife (Diocletian's daughter) Galeria Valeria the title of Augusta.source
  • 308November 11 – The Conference of Carnuntum: Attempting to keep peace within the Roman Empire, Galerius recalls Diocletian briefly from retirement, and they convene with Maximian. Diocletian persuades Maximian to return to retirement, and he and Galerius declare Maxentius a public enemy. Licinius is proclaimed Augustus of the west, while rival contender Constantine I is again declared Caesar.source
  • 311December 3 – Diocletian, Roman emperor (b. 244)source
  • 313At the end of 312 or in early 313, the retired Emperor Diocletian dies in his palace in Split, most likely from natural causes.source
  • 315Prisca, Roman empress and wife of Diocletian (b. 247)source

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