Claims to the throne from Old Rome and New Rome

Originally posted by Maju On the other hand, Charles had the Roman legality of military power... I don't think that Octavius or Constantine would have thought the claim of Charles lacking legitimacy, whatever their consideration on Papal intervention.

I agree....too many "legal" roman emperors came to power based on military might alone.  How many generals were declared emperor by their armies during the civil wars of the 3rd century?  What difference did legitimacy make?  Besides, even in the glory years of the western empire, there was no process for imperial sucession, especially once the praetorians started to murder their bosses.  This discussion is clouded by the view of filial succession from the kingdoms of medieval Europe.

Originally posted by Maju ...the Church provided the ideological legitimacy for political structures and also provided the bureaucracy. This is not a matter that affects the Eastern Empire but an inner affair of the former Western Empire, where the moral authority of the Papacy had become overwhelming due mostly to its claim of representing God on Earth (nothing less!). So the coronation of Charlemagne by the Pope can be dubbed of technically ilegal but it was obviously very legitimate in the sociological sense of the term. On the other hand, Charles had the Roman legality of military power... I don't think that Octavius or Constantine would have thought the claim of Charles lacking legitimacy, whatever their consideration on Papal intervention.

I will maintain the coronation of Charlemagne was almost exclusively a reactionary move against the Byzantines.  The Papacy resented Byzantium, partly because the Empire tried with little success to control the exarchate of Italy (including Papal lands), and this made the Popes angry.  After the fall of the Western principate, there was a political vacuum and the Popes wanted to fill that vacuum, with the Papacy becoming the central authority, both spiritually and physically (through temporal authorities, i.e. Charlemagne) in Western Europe.  Also, the Popes resented the Byzantines because they could not provide the military assistance to keep the Lombards and other barbarians off Papal territory.  That is why it turned to the most powerful group in Western Europe at the time, the Franks.  So in effect, the Papacy wanted it both ways and thumbed its nose at Byzantium when its demands remained unfulfilled.

I think at this point the imperium of Byzantium was still respected in theory if not in action in the West.  The idea of the Roman Empire was still around but fading more and more.  The papacy, on the other hand, was a viable force in Christendom at this time, but not yet one the level that it was during the Crusades and the Renaissance.  Along with the barbarians, it was trying to assert itself in the power vacuum in Western Europe.  Since Constantine fused Christianity with Roman imperium, the position of Roman emperor was already considered to be blessed by God.  The pope crowning someone did not neccessarily at this time confer legitimacy upon that person.

Yes, but the Byzantines equated that word with the Latin imperator or princeps.  Even though it seems snobbish, I am sure the Byzantines did not care what the West thought about its legitimacy.  It all has to do with an idea that was cemented into the Byzantine mindset.  Byzantium is the Roman Empire and the basileus is the ruler of all Christendom - this mindset remained all the way down to 1453, if not 1461. 

See this source for more information:

George Ostrogorsky. "The Byzantine Emperor and the Hierarchical World Order." Slavic and Eastern European Review 35 (1956-1957): 1-14.