During the late Republican period, generations of class conflict led to changes in the way Rome was governed and the way the people looked at their elected representatives. By the time of Julius Caesar or his successor Octavian (Augustus), the Republic had been replaced by a principate. This is the period of Imperial Rome. Augustus was the first princeps.
For almost 500 years, emperors passed on the mantle to their chosen successors, except when the army or the praetorian guards staged one of their frequent coups. Originally Romans ruled, but as time and the Empire spread, as barbarian settlers supplied more and more manpower for the legions, men from throughout the Empire came to be named emperor.
Emperor Diocletian divided the Empire into 4 sections controlled by 4 individuals, with 2 overlord emperors and 2 subordinate. One of the top emperors was stationed in Italy; the other, in Byzantium. Although the borders of their areas changed, the two-headed empire gradually took hold. By the time Rome "fell", in A.D. 476, to the so-called barbarian Odoacer, the Roman Empire was still going strong in its eastern capital, which had been created by Emperor Constantine and renamed Constantinople.
