John VI Cantacuzene

John VI Cantacuzene (c. 1292-1383), Byzantine emperor (1347-1355). He was the friend and first minister of the Byzantine emperor Andronicus III Palaeologus, after whose death he claimed the throne and went to war against the defenders of the legitimate heir, nine-year-old John V Palaeologus. Cantacuzene triumphed through the aid of the Ottoman Turks and is considered responsible for their entry into Europe. He had reigned only seven years when Palaeologus, having come of age, enlisted the aid of the Genoese and forced him to abdicate. He subsequently became a monk and wrote his memoirs, one of the major documents of Byzantine history. Cantacuzene also wrote a defence of Hesychasm, a Greek mystical doctrine.