History of the Roman Empire
Theodosius was the last Emperor who ruled over the whole Empire. After his death in 395, he gave the two halves of the Empire to his two sons Arcadius and Honorius; Arcadius became ruler in the East, with his capital in Constantinople, and Honorius became ruler in the West, with his capital in Milan and later Ravenna. The Roman state would continue to have two different emperors with different seats of power throughout the 5th century, though the Eastern Romans considered themselves to be the only ones who were fully Roman. Latin was used in official writings as much as, if not more than, Greek and the two halves were nominally, culturally and historically, if not politically, the same state.
Probus (emperor)
According to the favorable treatment of Gibbon (whose account is largely derived from the "Augustan History"), Probus was the last of the benevolent constitutional emperors of Rome. While his successor Carus (Imp. 281-284) simply disdained to seek the senate's confirmation of his title, the latter's successor Diocletian (Imp. 284-305) took active measures to undermine its authority, and established the autocratic nature and divine deriviation of the Imperial power. Never again, after Diocletian's reforms, would the Roman senate play an active role in the management of the empire. On the military sphere, Probus' victories continued the succession of martial Illyrian emperors begun by Claudius Gothicus, which restored the military supremacy of Rome after defeats sustained during the crisis of the third century.Attribution: