Louis II of Italy

Louis II became king of Italy in 844 at nineteen, co-ruling with his father Lothair I until the latter's death in 855 left him sole emperor. For most of his reign he used the standard title imperator augustus, but his 871 conquest of Bari from Muslim forces emboldened him to claim imperator Romanorum - a move that soured relations with the Eastern Roman Empire, which saw itself as the rightful heir to Rome. The Byzantines pointedly called him "Emperor of Francia" while West Francia labeled him "emperor of Italy," each refusing the grander claim. He ruled until his death on 12 August 875. The chronicler Andreas of Bergamo wrote that "after his death a great tribulation came to Italy."