Excerpts from Books and Wikipedia
"And for neither the first nor the last time in history, the lack of a viable succession or a vigorous heir had dire consequences. The era of the long reigns of the Andalusian Umayyads was at an end: al-Hakam, who was already forty-five when he inherited the caliphate from his long-reigning father in 961, died fifteen years later, leaving only an eleven-year-old son, the new caliph Hisham II, to succeed him. In a story that is archetypal and literary in nearly all its details, actual power was seized by an evil chamberlain who at first pretended to play the role of regent but whose own tyrannical control grew over the years, until the young man who was the rightful ruler ended as a powerless prisoner within his own palace walls. The caliphate was mortally wounded by this unpredictable turn of events, and by the havoc wrecked during the quarter-century of dictatorship and often bloodthirsty military rampages of that pretend regent, Ibn Abi Amir, infamously known as al-Mansur, 'the Victorious.' . . . Against the Christian territories to the north, campaigns that under his leadership acquired a fanatical and ideological pitch scarcely seen before." [Menocal: Ornament of the World, p. 96-7]