Leo IV the Khazar (Greek:Λέων ὁ Χάζαρος,romanized: Léōn hoKhazaros; 25 January 750 – 8 September 780) wasByzantine emperor from 775 to 780AD. He was born to EmperorConstantine V and EmpressTzitzak in 750. He was elevated to co-emperor in the next year, in 751, and married toIrene of Athens in 769. When Constantine V died in September 775, while campaigning against theBulgars, Leo IV became senior emperor. In 778 Leo raidedAbbasid Syria, decisively defeating the Abbasid army outside ofGermanikeia. Leo died on 8 September 780, of tuberculosis. He was succeeded by his underage sonConstantine VI, with Irene serving as regent.
Leo IV was born on 25 January 750AD,[2] to EmperorConstantine V and his first wife, EmpressTzitzak who had been given the Christian name Eirene.[3] Because his mother was aKhazar, Leo was given theepithet 'the Khazar'.[4] Leo was elevated to co-emperor in 751, while still an infant.[3] He became emperor on 14 September 775, after Constantine V died while campaigning against theBulgarian Empire.[5][6]
Leo was by this point suffering fromtuberculosis, which, combined with the infancy of his son,Constantine VI, gave two of Leo's half-brothers, thecaesaresNikephoros andChristopher, hope of attaining the throne. These hopes were crushed when, in 776, Leo elevated Constantine tocaesar, declaring him to be his successor. Shortly after this, Nikephoros and Christopher were discovered conspiring against Leo. Despite public opinion supporting the execution of the pair, Leo instead chose to pardon them, although he did exile several other plotters toCherson.[4][3][7]
In 776–777, KhanTelerig ofBulgaria sought refuge inConstantinople, was baptized in the presence of Leo and married a relation of the empress consortIrene of Athens. This demonstrates close relations between the Byzantine Empire and the Bulgars during Leo's reign, which were facilitated by his father Constantine V's successful campaigns against them between 760 and 775, establishing a state of peace.[8]
Leo continued with his father's resettlement policies, relocating prisoners from cities on the Arab border (Germanikeia,Melitene andTheodosioupolis) to newly-constructed military encampments or fortresses (castra) inThrace.[9]
Caliphal-Mahdi (r. 775–785) of theAbbasids launched an invasion of the Byzantine Empire in 776 with himself present.[10] The Byzantines retaliated in 778, invadingSyria with a force made up of the armies of the multiplethemes, including: theOpsikion Theme, led byGregory; theAnatolic Theme, led by Artabasdos; theArmeniac Theme, led byKaristerotzes; theBucellarian Theme, led byTatzates; and theThracesian Theme, led by the favourite commander of the Isaurian dynasty,Michael Lachanodrakon.[11] Lachanodrakon besiegedGermanikeia for a time, then lifted the siege (according toTheophanes the Confessor, he was bribed to do so) and began to raid the surrounding countryside, deporting manyJacobite Christians to Thrace.[10] The Abbasids attacked Lachanodrakon while he was raiding, but were decisively defeated by several Byzantine armies. The Byzantine generals who led troops during this battle were given atriumphal entry when they returned to Constantinople. In 779, Leo successfully repelled an attack by the Abbasids againstAsia Minor.[11]
Leo died of a violent fever, due to his tuberculosis, on 8 September 780. Nine-year-old Constantine became the new emperor with Irene as his regent.[12][13]
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