Matters of Charlemagne's reign came to a head in late 800. In 799,
Pope Leo III had been mistreated by the Romans, who tried to put out his eyes and tear out his tongue. He was deposed and put in a monastery. Charlemagne, advised by
Alcuin of York, refused to recognise the deposition. He travelled to Rome in November 800 and held a council on
December 1. On
December 23, Leo swore an oath of innocence. At
Mass, on Christmas Day (
December 25), the pope crowned Charlemagne
Imperator Romanorum (Emperor of the Romans) in
Saint Peter's Basilica. Einhard says that Charlemagne was ignorant of the pope's intent and did not want any such coronation:
he at first had such an aversion that he declared that he would not have set foot in the Church the day that they [the imperial titles]
were conferred, although it was a great feast-day, if he could have foreseen the design of the Pope. Charlemagne thus became the renewer of the
Western Roman Empire, which had expired in 476. To avoid frictions with the
Byzantine Empire, Charles later styled himself, not
Imperator Romanorum (a title reserved for the Byzantine emperor), but rather
Imperator Romanum gubernans Imperium (emperor ruling the
Roman Empire).