Western Roman Empire

The Western Roman Empire was the western half of the Roman Empire, the other half being the Eastern Roman Empire or Byzantine Empire. Administrative division of the sprawling Empire into a Western and Eastern half with co-emperors for each began under Diocletian in 285 and was periodically abolished and recreated for the next two centuries until final abolishment by the Byzantine emperor Zeno in 480. By that time there was little effective control left in the Western Empire.

A 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 (324–363). Theodosius I divided the Empire upon his death (in 395) between his two sons. Eighty-five years later, Zeno would recognize the reality of the Western Empire's reduced domain (Imperial control had been lost over even the Italian Peninsula) after the death of Western Emperor Julius Nepos and rule as sole emperor.

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.

The ongoing struggle between the rising Papacy and the retreating empire led the Pope to unilaterally declare the Frankish King Charlemagne to be the successor of the Western Emperors in 800. This new imperial line would evolve in time into the Holy Roman Empire, which revived the imperial title but was otherwise in no meaningful sense an extension of Roman traditions or institutions. After 924 it was also a primarily Germanic empire that contained little of the former territory of the Western Roman Empire.