When did Napoleon crown himself emperor?
Coronation of Napoleon I
{'answer_start': array([-1]), 'answer_text': array([''], dtype=object)}
Dwyer, Philip. "Citizen Emperor’: Political Ritual, Popular Sovereignty and the Coronation of Napoleon I,"  History (2015) 100#339 pp 40–57, 
Masson, Frederic; Cobb. Frederic (translator). Napoleon and his Coronation. London, 1911