History of Europe
In 395 Theodosius I, who had made Christianity the official religion of the Roman Empire, would be the last emperor to preside over a united Roman Empire. The empire was split into two halves: the Western Roman Empire centred in Ravenna, and the Eastern Roman Empire (later to be referred to as the Byzantine Empire) centred in Constantinople. The Roman Empire was repeatedly attacked by Hunnic, Germanic, Slavic and other “barbarian” tribes (see: Migration Period), and in 476 finally the Western part fell to the Heruli chieftain Odoacer.
Prince-elector
From the 13th century onwards, the Prince-Electors had the privilege of electing the King of the Romans, who would be crowned by the Pope as Holy Roman Emperor. Charles V was the last to be a crowned Emperor (elected 1519, crowned 1530); his successors were elected Emperors directly by the electoral college, each being titled "Elected Emperor of the Romans" (; ). In practice, every emperor from 1440 onwards (except for Charles VII and Francis I) came from the Austrian House of Habsburg, and the Electors merely ratified the Habsburg succession.