Governing Senate
On 31 October 1721, Peter I was proclaimed Emperor by the Governing Senate. The title used was Latin ""Imperator", which is a westernizing form equivalent to the traditional Slavic title "Tsar"". He based his claim partially upon a letter discovered in 1717 written in 1514 from Maximilian I to Vasili III, in which the Holy Roman Emperor used the term in referring to Vasili.