Constantine VI was the only child of Emperor Leo IV and Irene. Constantine was crowned co-emperor by his father in 776, and succeeded as sole emperor in 780, at the age of nine. Due to his minority, Irene and her chief minister Staurakios exercised the regency for him.
In 787 Constantine had signed the decrees of the Second Council of Nicaea, but he appears to have had iconoclast sympathies. By then Constantine had turned 16 years old, but his mother did not relinquish executive authority to him.
In 788, Irene herself broke off the engagement of Constantine with Rotrude, a daughter of Charlemagne. Turning against Charlemagne, the Eastern Romans now supported Lombard pretender Adalgis, who had been forced into exile after the Frankish invasion of Italy. Adalgis was given command of a Roman expeditionary corps, landing in Calabria towards the end of 788 but was defeated by the united armies of the Lombard dukes Hildeprand of Spoleto and Grimoald III of Benevento as well as Frankish troops under Winiges.
After a conspiracy against Irene was suppressed in the spring of 790 she attempted to get official recognition as empress. This backfired and with military support Constantine finally came to actual power in 790, after the Armeniacs rebelled against Irene. Nevertheless, she was allowed to keep the title of Empress, which was confirmed in 792.
Once in control of the state, Constantine proved incapable of sound governance. His army was defeated by the Arabs, and Constantine himself suffered a humiliating defeat at the hands of Kardam of Bulgaria in the 792 Battle of Marcellae. A movement developed in favor of his uncle, the Caesar Nikephoros. Constantine had his uncle's eyes put out and the tongues of his father's four other half-brothers cut off. His former Armenian supporters revolted after he had blinded their general Alexios Mosele. He crushed this revolt with extreme cruelty in 793.
He then divorced his wife Maria of Amnia, who had failed to provide him with a male heir, and married his mistress Theodote, an unpopular and canonically illegal act which sparked off the so-called "Moechian Controversy". Although the Patriarch Tarasios did not publicly speak against it, he did refuse to officiate the marriage. Popular disapproval was expressed by Theodote's uncle, Plato of Sakkoudion, who even broke communion with Tarasios for his passive stance. Plato's intransigence led to his own imprisonment, while his monastic supporters were persecuted and exiled to Thessalonica. The "Moechian Controversy" cost Constantine what popularity he had left, especially in the church establishment, which Irene took care to vocally support against her own son.
On 19 April 797 Constantine was captured, blinded, and imprisoned by the supporters of his mother, who had organized a conspiracy, leaving Irene to be crowned as first Empress regnant of Constantinople. It is unknown when exactly Constantine died; it was certainly before 805, but he very likely died of his wounds shortly after being blinded. He was buried in the Monastery of St. Euphrosyne, which Irene had founded.
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By his first wife Maria of Amnia, Constantine VI had two daughters:
Constantine VIBorn: 771 Died: before 805
8 September 780– August 797