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.
The Last Legion
Orestes, who was partly of Germanic blood, was historically the "magister militum" – the senior officer of the Roman army second to the emperor. He had indeed promised his Germanic foederati a third of Italy to settle in but not to Odoacer personally. Orestes was himself a usurper, having promised the land to foederati to buy their quiescence in his rebellion against the legitimate emperor Julius Nepos. Although Orestes proclaimed his son, Romulus Augustus (derisively called "Augustulus", meaning "little Augustus") Emperor, the proclamation was not recognised as legitimate beyond the parts of the Italian Peninsula controlled by Orestes' troops. The common identification of Augustus as the "last Western Emperor" dates only from the publication of British historian Edward Gibbon's History of the Decline and Fall of the Roman Empire in the late 18th Century.