The coronation of Charles was the central event of the Middle Ages.[1]It arrested the downward trajectory of (chaos) in the West and established a new paradigm of power and rule which was to prevail until the accession of Charles V in 1519. Pope Leo’s crowning of Charles was a deliberate, conspicuous declaration of the unification of the temporal might of the Franks with the spiritual authority of Rome. Although such a union had been effected previously by Charlemagne’s father Pippin III and Pope Stephen II, it had not been done with such ostentation and pageantry, not on such a propitious day – Christmas Day 800 was not only a central Christian holy day, but was believed to be exactly 7000 years since the creation –  and certainly not in Rome, the city of the Caesars and the most important city in western Christendom.[2] Moreover, Pippin was anointed only as King; not as a Roman Emperor. Charlemagne’s coronation was nothing less than a desire to revive the glory of Rome and its legitimacy, its power, integrity and its unity. It was, in essence, a longing after the mirage of Rome.  

[1] Viscount James Bryce. http://www.gutenberg.org/files/44101/44101-h/44101-h.htm#Page_52

[2] Wilson. The Holy Roman Empire pg 27