Leo was the son of the patrician Bardas, who was of
Armenian descent (according to a later source, Leo was also of
Assyrian descent). Leo served in 803 under the rebel general Bardanes Tourkos, whom he deserted in favor of Emperor
Nikephoros I. The emperor rewarded Leo with two palaces, but later exiled him for marrying the daughter of another rebel, the patrician Arsaber. On the other hand, a contemporary source says that one general Leo of Armeniakon theme was punished for his humiliating defeat by the Arabs during which he also lost the salaries of his thematic units (a modern scholar suggests that this Leo is not the same with the emperor). His punishment also included depriving of his military rank, beating and hair cutting).
Recalled by
Michael I Rangabe in 811, Leo became governor of the Anatolic theme and conducted himself well in a war against the
Arabs in 812. Leo survived the
Battle of Versinikia in 813 by abandoning the battlefield, but nevertheless took advantage of this defeat to force the abdication of Michael I in his favor on
July 11, 813. In a diplomatist move, he wrote a letter to
Patriarch Nikephoros in order to reassure him of his orthodoxy (Nicephorus being obviously afraid of a possible
iconoclasm revival). One month later, during his entrance to the Palace quarter, he kneeled before the icon of Christ at the Chalke Gate. A further step in preventing future usurpations was the castration of Michael's sons.
With
Krum of Bulgaria blockading
Constantinople by land, Leo V had inherited a precarious situation. He offered to negotiate in person with the invader and attempted to have him killed in an ambush. The stratagem failed, and although Krum abandoned his siege of the capital, he captured and depopulated
Adrianople and Arkadioupolis (
Lüleburgaz). When Krum died in spring 814, Leo V defeated the
Bulgarians in the environs of Mesembria (
Nesebar) and the two states concluded a 30-year peace in 815. According to some sources, Krum participated in the battle and abandoned the battlefield heavily injured.
With the
iconodule policy of his predecessors associated with defeats at the hands of Bulgarians and Arabs, Leo V reinstituted
Iconoclasm after deposing patriarch Nikephoros and convoking a synod at Constantinople in 815. The emperor used his rather moderate iconoclast policy to seize the properties of iconodules and monasteries, such as the rich
Stoudios monastery, whose influential iconodule abbot,
Theodore the Studite, he exiled.
Leo V appointed competent military commanders from among his own comrades-in-arms, including
Michael the Amorian and
Thomas the Slav. He also persecuted the
Paulicians. When Leo jailed Michael for suspicion of conspiracy, the latter escaped from prison and organized the
assassination of the emperor in the cathedral
Hagia Sophia on
Christmas, 820. Leo was praying alone before the altar, with his guards standing outside the church.
The conspirators were disguised as priests and monks led by Michael who had been set free by his partisans only hours before entering the church.
When they approached Leo they drew their daggers to stab him.
Leo, suspecting something was wrong, jumped away when he saw the daggers and tried to flee and call for his guards, but the doors were locked and his guards were slain by the conspirators.
Unarmed, Leo tried to defend himself with a large wooden cross in one hand and an incense burner with the other, attacking Michael and his followers.
This battle lasted for an hour and finally Leo succumbed to the wounds inflicted upon him.
Michael was immediately proclaimed Emperor on the spot still wearing the chains from the prison in his hands. Leo's family (including his mother and his wife Theodosia) was exiled to monasteries in
Princes' Islands. His four sons (including ex co-emperor Symbatios) were castrated but one of them died during the "operation".
Even sources vehemently hostile to Leo (Theophanes Continuatus, patriarch Nikephoros) acknowledge his competence in managing state affairs. Unfortunately, as with all iconoclast emperors, his actions and intentions cannot be easily reconstructed due to the extreme bias of the iconodule sources (there are no surviving contemporary iconoclast sources of any kind).
