Reigned from December 16, 955 to May 14, 964. Born in Rome, Italy, c.937as Octavius; died there. A son of Alberic II, his election was secured by his father. He opened his pontificate with an appeal to Otto I for aid against Berengarius, King of Italy. He crowned Otto emperor in 962, and shortly after received the Ottonian Diploma which confirmed the papacy in its possessions. John now turned against Otto who was assuming papal prerogatives, but was forced to flee before the latter's army. A synod convened in Saint Peter's in 963 summoned the pope to answer for his crimes. He refused to recoguize it and was deposed, while a layman, the antipope Leo VIII, was elected in his stead; the proceeding was uncanonical and the election regarded as invalid. John took sanguinary measures of reprisal, but died as Otto was preparing to return to Rome.