Irene’s rule was one factor behind Charlemagne’s imperial coronation on 24 December 800, reshaping western ideas of Roman legitimacy.
On 24 December 800, Irene’s usurpation of the imperial throne helped create the conditions under which Charlemagne was crowned emperor in the West. Latin Christian observers and papal authorities used the presence of a woman on the Byzantine throne as part of the political logic for establishing a separate western imperial title. Irene did not directly crown Charlemagne, but her rule was a key background factor in the unfolding of the event.
This moment was historically important because it hardened the division between eastern and western imperial legitimacy. Irene’s reign demonstrated that Byzantine power could be embodied by a female sovereign, but it also exposed the instability of that arrangement in the eyes of western elites. The result was a new imperial order in which the papacy and Carolingian monarchy advanced a rival claim to Roman authority. Irene’s name therefore belongs not only in Byzantine history but also in the broader history of medieval Europe, where her accession helped reshape the symbolic map of empire.