The Western Roman Empire refers to the western half of the Roman Empire, from its division by Diocletian in 286; the other half of the Roman Empire became known as the Eastern Roman Empire, today widely known as the Byzantine Empire. The capital of the Western Roman Empire was in Mediolanum (modern Milan), until it was moved to Ravenna in 402. The Western Empire existed intermittently in several periods between the 3rd century and 5th century, after Diocletian's Tetrarchy and the reunifications associated with Constantine the Great and Julian the Apostate. Theodosius I was the last Roman Emperor who ruled over a unified Roman empire. After his death in 395, the Roman Empire was permanently divided. The Western Roman Empire ended officially with the abdication of Romulus Augustus under pressure of Odoacer on 4 September476, and unofficially with the death of Julius Nepos in 480.
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Noun 1. the western part after the Roman Empire was divided in 395; it lasted only until 476 (synonym) Western Empire (hypernym) geographical area, geographic area, geographical region, geographic region (part-holonym) Roman Empire