22 Dec. 244: Date of birth of Diocletian (Diocles) at Salona, near Spalatum.
265: He begins his military career under Gallienus.
270: He serves in Gaul in the reign of Aurelius.
282: He becomes Dux Moesiae under Carus.
283: He becomes commander of the imperial bodyguard under Numerianus.
20 November 284: He is proclaimed as emperor by the army and he is named Diocletian.
285: Battle at Margus. Carinus, Numerianus’ brother and legitimate successor to the throne, is killed. Diocletian is acknowledged as emperor by the Senate.
286: Maximian is proclaimed as co-emperor; beginning of ‘dyarchy’ with the symbol of concord.
288: Diocletian’s great victory against Vahram, a Sasanid.
289: War against the Sarmatians.
290: War against the Saracens in Syria.
291: Suppression of a revolt by natives in Egypt.
293: ‘Tetrarchy’: Constantius Chlorus is appointed Caesar of Maximian (marries his granddaughter Theodora) and Galerius is appointed Caesar of Diocletian (marries his daughter Valeria).
294/295: Diocletian begins his reforms in the East. Changes in administration and economy; division of the military and the political power.
296: Maximian succeeds in suppressing the rebellion in Britain, killing the pretender of the throne Carausius.
297: Diocletian quells another revolt in Egypt and Galerius defeats the Sasanids led by Narses.
301: Diocletian issues the Edict on Maximum Prices in an attempt to curb inflation.
303: Diocletian issues the edict for the persecution of the Christians of Nicomedia, which soon expands all over the East mainly by Galerius. His wife Prisca is obliged to make sacrifices to the Roman gods.
305: Diocletian and Maximian abdicated. The Caesars become Augusti and Flavius Valerius Severus and Maximinus Daia are appointed new Caesars.
311/312: Prisca and Valeria are exiled to Syria by Maximinus Daia.
315: Prisca and Valeria are executed by Licinius in Thessaloniki.
3rd December 316: Death of Diocletian, aged 71.