260: Sapor captures Valerian; Postumus establishes imperium Galliarum.
262: Gallienus appoints Odaenathus corrector totius orientis; issues rescript restoring Christian property seized during the persecution in the east.
268: Odaenathus murdered; Gallienus murdered; Claudius II proclaimed Augustus.
269: Claudius wins victory at Naissus; Zenobia claims Odaenathus’ position.
270: Palmyrene conquest of Egypt; death of Claudius; Aurelian proclaimed Augustus; death of Sapor I
272: Aurelian captures Palmyra.
273: Aurelian reforms imperial silver coinage.
275: Aurelian murdered; Tacitus proclaimed Augustus.
276: Tacitus murdered; Probus becomes Augustus.
282: Probus murdered; Carus becomes Augustus, begins invasion of Persia; birth of Constantine on February 27 (?)
283: Carus dies (is murdered) in Mesopotamia; Numerian succeeds as co-Augustus with Carinus.
284: Numerian murdered, Diocletian proclaimed Augustus (November 20).
285: Diocletian defeats Carinus; Diocletian appoints Maximian Caesar.
286: Diocletian elevates Maximian to the rank of Augustus (April 1).
287: Revolt of Carausius begins in northern Gaul and Britain.
289: Marriage of Constantius and Theodora (before April 21 of that year).
293: Constantius and Galerius made Caesars; murder of Carausius; Allectus becomes ruler in Britain.
296: Constantius recovers Britain; outbreak of war between Rome and Persia.
298: Galerius defeats Persians.
299: Treaty between Rome and Persia; birth of Fausta (?)
303: Diocletian promulgates first persecution edict against Christians (February 24).
305: Diocletian and Maximian abdicate; Constantius and Galerius become Augusti; Severus and Maximinus Daia becomes Caesars.
306: Constantius dies at York (July 25); Constantine proclaimed Caesar by the army in Britain; Maxentius claims the imperial power at Rome (October 28).
307: Marriage of Constantine and Fausta; Constantine restores Christian property confiscated under the persecution edict in his part of the empire; Severus imprisoned by Maxentius; Galerius fails to suppress revolt of Maxentius; Severus murdered on orders of Maxentius.
308: Maximian is received by Constantine in Gaul; council at Carnuntum; Licinius appointed Augustus by Galerius.
310: Maximian rebels against Constantine, fails, and commits suicide.
311: Deaths of Galerius and Diocletian
312: Probable date for Constantine’s conversion to Christianity; Constantine invades Italy, defeats Maxentius at the battle of the Milvian Bridge on October 28; Maximinus Daia ends persecution of Christians.
313: Licinius defeats Maximinus Daia; Licinius’ “Edict of Nicomedia” confirms end of persecution of Christians in the east.
314: Council of Arles to discuss the Donatist Controversy.
316: Birth of Constantine II (August 7); Constantine attacks Licinius; battle of Cibalae (October 8).
317: Battle of Adrianople; Licinius surrenders two Balkan dioceses to Constantine; birth of Constantius II (August 7).
323: Birth of Constans
324: Constantine defeats and deposes Licinius; selects Byzantium (Constantinople) as the site for a new capital.
325: Council of Nicaea (June)
326: Execution of Crispus Caesar; Fausta removed from public life.
327: Helena makes trip to the Holy Land.
328: Death of Helena
330: Dedication of Constantinople (May 11–12)
337: Death of Constantine (May 22); Constantine II, Constans, and Constantius II become Augusti (September 9).
350: Constans murdered; Magnentius becomes Augustus in the western empire (January 18).
351: Constantius appoints Gallus as Caesar (March 15).
353: Constantius reunites empire; Magnentius commits suicide (August 10).
354: Gallus executed.
355: Constantius appoints Julian Caesar in Gaul (November 6).
360: Julian proclaimed Augustus in Gaul without Constantius’ permission.
361: Julian invades the eastern empire; death of Constantius II (November 3); Julian proclaims allegiance to traditional gods.