Problem of two emperors

The problem of two emperors or two-emperors problem (deriving from the German term Zweikaiserproblem, πρόβλημα δύο αυτοκρατόρων) is the historiographical term for the historical contradiction between the idea of the universal empire, that there was only ever one true emperor at any one given time, and the truth that there were often multiple individuals who claimed the position simultaneously. The term is primarily used in regards to medieval European history and often refers to in particular the long-lasting dispute between the Byzantine emperors in Constantinople and the Holy Roman emperors in modern-day Germany and Austria as to which monarch represented the legitimate Roman emperor. In the view of medieval Christians, the Roman Empire was indivisible and its emperor held a somewhat hegemonic position even over Christians who did not live within the formal borders of the empire. Since the collapse of the Western Roman Empire during late antiquity, the Byzantine Empire (which represented its surviving provinces in the East) had been recognized as the legitimate Roman Empire by itself, the pope, and the various new Christian kingdoms throughout Europe. This changed in 797 when Emperor Constantine VI was deposed, blinded, and replaced as ruler by his mother, Empress Irene, whose rule was ultimately not accepted in Western Europe, the most frequently cited reason being that she was a woman. Rather than recognizing Irene, Pope Leo III proclaimed the king of the Franks, Charlemagne, as the emperor of the Romans in 800 under the concept of translatio imperii (transfer of imperial power). Although the two empires eventually relented and recognized each other's rulers as emperors, they never explicitly recognized the other as "Roman", with the Byzantines referring to the Holy Roman emperor as the 'emperor (or king) of the Franks' and later as the 'king of Germany' and the western sources often describing the Byzantine emperor as the 'emperor of the Greeks' or the 'emperor of Constantinople'.