He was one of the victims of the reign of terror unleashed by the usurper
Andronikos I Komnenos (reigned 1183–1185) in 1183, who had him
blinded, though possibly not completely, then thrown into prison, because he attacked a court eunuch who blamed the disasters befalling the empire on the incompetence of Andronikos' predecessor, his under-age nephew
Alexios II Komnenos ().
Donald Nicol argues this shows he was a partisan of the
House of Angelos, and he had his reward when
Isaac II Angelos () came to the throne in 1185: the new emperor give him the rank of
Caesar and appointed him to command
the expedition against the Bulgarians in 1186, who had recently rebelled against the Byzantine rule and had
restored the Bulgarian Empire. The rebels did not oppose the Byzantines in the open field, and instead retired to their mountain stronghold. John followed them there, but due to his overconfidence neglected to fortify his camp and allowed it to be surrounded, suffering a humiliating defeat. His robes of office were captured and displayed by the
Bulgarian leaders
Peter and
Asen. John was relieved of command by the Emperor in favour of
Alexios Branas, and lived in retirement. He married Irene Angelina, daughter of
Andronikos Doukas Angelos and sister of the emperors Isaac II and
Alexios III Angelos (). The marriage was first disallowed by the
Patriarch of Constantinople,
Luke Chrysoberges, and the then-reigning emperor,
Manuel I Komnenos (), because a seventh degree of consanguinity existed between John and Irene. However, in 1185/86, after Isaac Angelos came to power, a synod overthrew Patriarch
Basil II Kamateros—an appointee of Andronikos I—and the new patriarch,
Niketas Mountanes, gave his approval to the marriage. They appear to have had a son, for the man was put forth as a possible candidate to the throne during the illness of Alexios III. John's parents are not known, but he may have been brother to Theodore Kantakouzenos (died 1184), whom
Niketas Choniates states was killed assisting Isaac Angelos defend the city of
Nicaea against Andronikos Komnenos. == References ==