284    Diocletian is proclaimed emperor by his soldiers.

284    Diocletian is chosen as Roman Emperor.

285    Diocletian appoints Maximian as Caesar and co-ruler.

285    Diocletian appoints Maximian as Caesar, co-ruler.

286    Roman Emperor Diocletian raises Maximian to the rank of ''Caesar''.

303    Diocletian, Roman Emperor, publishes his edict that begins the persecution of Christians in his portion of the Empire.

305    Diocletian and Maximian retire from the office of Roman Emperor.

308    At Carnuntum, Emperor ''emeritus'' Diocletian confers with Galerius, ''Augustus'' of the East, and Maximianus, the recently returned former ''Augustus'' of the West, in an attempt to restore order to the Roman Empire.