[3][4] His mother was also of Armenian origin, the daughter of the patrikios Arsaber who attempted an unsuccessful usurpation against Nikephoros I in 808.

[2][6] At the head of a military revolt following the disastrous Battle of Versinikia against the Bulgars, Leo deposed Michael I on 11 July 813 and was crowned emperor on the next day.

Leo's motivations can only be guessed at, but at a time when the environs of Constantinople itself were being raided by the Bulgar ruler Krum, the military successes achieved by the iconoclast emperors contrasted starkly with the defeats suffered by the recent iconophile regimes.

[14][15] On 14 March 814, Leo forced the resignation of Patriarch Nikephoros I, and appointed the pro-iconoclast Theodotos Melissenos, the son of one of Constantine V's brothers-in-law, in his place.

They spent the rest of their days there as monks, although Michael the Amorian allowed them to keep part of the proceeds from their confiscated estates for their and their servants' upkeep.