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.
Constitution of the Roman Empire
The general who won the last civil war of the Roman Republic, Gaius Octavian, became the master of the state. In the years after 30 BC, Octavian set out to reform the Roman constitution. The ultimate consequence of these reforms was the abolition of the republic and the founding of the Roman Empire. When Octavian deposed his fellow triumvir, Mark Antony, in 32 BC, he resigned his position as triumvir, but was probably vested with powers similar to those that he had given up. Octavian wanted to solidify his status as master of the state whilst avoiding assassination.