Leo was the son of the patrician Bardas, who was of Armenian descent (according to Theophanes Continuatus, Leo was also of 'Assyrian',[REF] that is Syrian,[REF]descent). Leo served in 803 under the rebel general Bardanes Tourkos, whom he deserted in favor of Emperor Nikephoros I.
With Krum of Bulgaria blockading Constantinople by land, Leo V had inherited a precarious situation.