Western Roman Empire

The term Western Roman Empire is used in modern historiography to refer to the western provinces of the Roman Empire, collectively, during any period in which they were administered separately from the eastern provinces by a separate, independent Imperial court—and particularly during the period from 395 to 476, in which there were separate, coequal courts dividing the governance of the empire in the Western provinces from that of the Eastern provinces, with a distinct imperial succession in the separate courts. The terms Western Roman Empire and Eastern Roman Empire were coined in modern times to describe political entities that were de facto independent; contemporary Romans did not consider the Empire to have been split into two empires but viewed it as a single polity governed by two imperial courts as an administrative expediency. The Western Roman Empire collapsed in 476, and the Western imperial court in Ravenna was formally dissolved by Justinian I in 554. The Eastern imperial court lasted until 1453. Though the Empire had seen periods with more than one emperor ruling jointly before, the view that it was impossible for a single emperor to govern the entire Empire was institutionalised with reforms to Roman law by emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the Third Century. He introduced the system of the tetrarchy in 286, with two senior emperors titled Augustus, one in the East and one in the West, each with an appointed Caesar (junior emperor and designated successor). Though the tetrarchic system would collapse in a matter of years, the East–West administrative division would endure in one form or another over the coming centuries. As such, the Western Roman Empire would exist intermittently in several periods between the 3rd and 5th centuries. Some emperors, such as Constantine I and Theodosius I, governed as the sole Augustus across the Roman Empire.