<P> In historiography, the Western Roman Empire consists of the western provinces of the Roman Empire at any one time during which they were administered by a separate independent Imperial court, coequal with that administering the eastern half . Both "Western Roman Empire" and "Eastern Roman Empire" (or "Byzantine Empire") are modern terms describing de facto independent entities; however, at no point did the Romans consider the Empire split into two, but rather considered it a single state governed by two separate Imperial courts out of administrative expediency, a system of government known as a diarchy . </P> <P> The view that the Empire was impossible to govern by one emperor was established by Diocletian following the disastrous civil wars and disintegration of the Crisis of the 3rd century, and was instituted in Roman law by his introduction of the Tetrarchy in AD 285, a form of government which was legally to endure in one form or another for centuries . There being more than one emperor at a time was not an unknown concept in the empire, as there had been multiple points in the past where more than one emperor ruled jointly . </P> <P> The Western Roman Empire existed intermittently in several periods between the 3rd and 5th centuries, after Diocletian's Tetrarchy and the reunifications associated with Constantine the Great and Julian the Apostate (331 / 2--363). Theodosius I divided the Empire upon his death (in 395) between his two sons . Finally, eighty - five years later in AD 480, Zeno of the Eastern Empire recognized the reality of the Western Empire's reduced domain--effective central control had ceased to exist even in the Italian Peninsula--after the deposition of Romulus Augustus and the subsequent death of Julius Nepos, and therefore abolished the Western court and proclaimed himself the sole emperor of the Roman Empire . </P> <P> The rise of Odoacer of the Foederati to rule over Italy in 476 was popularized by eighteenth - century historian Edward Gibbon as a demarcating event for the end of the Western Empire and is sometimes used to mark the transition from Antiquity to the Middle Ages . Imperial rule was reimposed in large parts of the West, including North Africa, Italy and parts of Hispania, in the sixth century by the armies of the Eastern Roman Empire under Emperor Justinian I. Political upheaval in the East Roman heartlands made efforts to retain control of these territories difficult and they were gradually lost, this time for good . </P>

The ruler of the holy roman empire that split his empire in half between his two sons was who