Answer
Nizar, a prominent figure in the Fatimid dynasty, revolted against the reigning caliph, Al-Musta'li. Nizar claimed to be the rightful successor to the throne, challenging Al-Musta'li's authority. This revolt led to a period of instability and conflict within the Fatimid Empire, as Nizar and his supporters sought to overthrow Al-Musta'li and establish their own rule.