Nizar was born on 26September 1045 (5 Rabīʿ al-ʾAwwal 437
A.H.) to the ruling
Fatimid imam–
caliph,
al-Mustansir (). At that time, al-Mustansir was around 15years old and had already been on the throne for ten years. Nizar was most likely the eldest son of the caliph, although another son named Abu Abdallah is sometimes listed as the senior of al-Mustansir's sons. In the late 1060s, the Fatimid Caliphate entered a profound crisis, with the advance of the
Seljuk Turks from the east threatening its hold over
Syria, and protracted clashes between the
Fatimid army's Turkish and
black African troops in
Egypt leading to the breakdown of the central government and widespread famine and anarchy. In about1068, as internal turmoil threatened the dynasty with collapse, al-Mustansir dispersed his sons throughout his territories as a safeguard, keeping only an unnamed underage son close to him. The account by the
Mamluk-era historian
al-Maqrizi says that Abu Abdallah and Abu Ali were to go to
Acre to join the army of the commander
Badr al-Jamali; Abu'l-Qasim Muhammad (father of the Caliph
al-Hafiz) to
Ascalon; while another, unnamed but underage son, remained in Cairo. Nizar is not mentioned by al-Maqrizi, but he was very likely included in this measure, and the , a proclamation issued in 1122 by Caliph
al-Amir (), claims that he was sent to the port of
Damietta. This dispersal of the Fatimid princes lasted at least until Badr al-Jamali assumed power in 1073 as
vizier and quasi-dictator and restored order in Egypt.
Disputed succession As the oldest son, Nizar was apparently considered to be his father's most likely successor, as was the custom; indeed, historians often state that Nizar had been his father's designated successor. However, no formal designation of Nizar as heir seems to have taken place by the time of al-Mustansir's death in December 1094. Al-Maqrizi writes that this was due to the machinations of Badr's son
al-Afdal Shahanshah, who had succeeded his father to the vizierate in June 1094. According to al-Maqrizi, a deep-seated enmity existed between al-Afdal and Nizar. An anecdote tells how al-Afdal had once tried to enter the palace on horseback—a privilege reserved for the caliph—whereupon Nizar yelled at him to dismount and called him a "dirty Armenian". Since then, the two had been bitter enemies, with al-Afdal obstructing Nizar's activities and demoting his servants, while at the same time winning the army's commanders over to his cause. Only one of them, the Berber Muhammad ibn Masal al-Lukki, is said to have remained loyal to Nizar, because he had promised to appoint him vizier instead of al-Afdal. According to al-Maqrizi, al-Afdal pressured al-Mustansir to prevent Nizar's public nomination as heir, and when the caliph died, al-Afdal raised a much younger half-brother of Nizar,
al-Musta'li, to the throne and the imamate. Al-Musta'li, who had shortly before married al-Afdal's sister, was completely dependent on al-Afdal for his accession. This made him a compliant figurehead who was unlikely to threaten al-Afdal's recent, and therefore as yet fragile, hold on power. In order to defend al-Musta'li's succession and counter the claims of Nizar's partisans, al-Mu'stali's son and successor, al-Amir, issued the . This document puts a different spin on the dispersal of the princes: supposedly, they were sent away in order of importance, with those closest to Cairo (and thus the caliph himself) being the highest in rank. Modern historians point out that this was a deliberately misconstrued argument, as the princes were sent away for their protection. According to the historian
Paul E. Walker, sending Abu Abdallah to the strong army of Badr al-Jamali was, if anything, an indication of his high importance and of his father's desire to keep him safe. At the same time, the unidentified underage son left in Cairo was clearly not al-Musta'li, who had not even been born yet. Walker identifies the unnamed prince with Abu'l-Qasim Ahmad, whose birth had been publicly announced in 1060. That prince had likely died in the meantime, as the future al-Musta'li, born in 1074, was given the same name. The and other accounts further assert the legitimacy of al-Musta'li's accession by reporting stories that on the wedding banquet of al-Musta'li, or on his deathbed, al-Mustansir had chosen him as his heir, and that one of al-Mustansir's sisters is said to have been called to him privately and received al-Musta'li's nomination as a bequest. Modern historians, such as
Farhad Daftary, believe these stories to be most likely attempts to justify and retroactively legitimize what was in effect a
coup d'état by al-Afdal. However, al-Maqrizi also includes a different narrative that casts doubt on whether al-Afdal's move was really a carefully prepared coup. When al-Afdal summoned three of al-Mustansir's sons—Nizar, Abdallah, and Isma'il, apparently the most prominent among the caliph's progeny—to the
palace to do homage to al-Musta'li, who had been seated on the throne, they each refused. Not only did they reject al-Musta'li, but each of them claimed that al-Mustansir had chosen him as his successor. Nizar claimed that he had a written document to this effect. This refusal apparently took al-Afdal completely by surprise. The brothers were allowed to leave the palace; but while Abdallah and Isma'il made for a nearby mosque, Nizar immediately fled Cairo. To add to the confusion, having learned of al-Mustansir's passing, Baraqat, the chief missionary () of Cairo (the head of the
Isma'ili religious establishment) proclaimed Abdallah as caliph with the regnal name . However, al-Afdal soon regained control. Baraqat was arrested (and later executed), Abdallah and Isma'il were placed under surveillance and eventually publicly acknowledged al-Musta'li. A grand assembly of officials was held, which acclaimed al-Musta'li as imam and caliph.
Rebellion and death In the meantime, Nizar fled to
Alexandria with a few followers. The local governor, a
Turk named
Nasr al-Dawla Aftakin, opposed al-Afdal, so Nizar was quickly able to gain his support. He also won over the local judge (), the inhabitants and the surrounding Arab tribes to his cause. He then rose in revolt and proclaimed himself imam and caliph with the title of ('the Chosen One for God's Religion'). A
gold dinar of Nizar, bearing this title, was discovered in 1994, attesting to his assumption of the caliphal title and the minting of coinage with it. According to Walker, the speed with which Nizar gained support, and some other stories narrated in al-Maqrizi, suggest the existence of a relatively large faction that expected or wanted him to succeed al-Mustansir. Nizar's revolt was initially successful: al-Afdal's attack on Alexandria in February1095 was easily repulsed, and Nizar's forces raided up to the outskirts of Cairo. Over the next months, however, al-Afdal managed to win back the allegiance of the Arab tribes with bribes and gifts. Weakened, Nizar's forces were pushed back to Alexandria, which was placed under siege. In November, Nizar's military commander Ibn Masal abandoned the city, taking most of the remaining treasure with him. This forced Aftakin and Nizar to surrender against a guarantee of their safety (). Both were taken back to Cairo, where Nizar was
immured and Aftakin was executed. The details or exact date of Nizar's death are unknown. In a surviving letter sent to the Isma'ili Yemeni queen
Arwa al-Sulayhi announcing his accession, al-Musta'li gives the "official" version of events as follows: Like the other sons of al-Mustansir, Nizar had at first accepted his imamate and paid him homage, before being moved by greed and envy to revolt. The events up to the capitulation of Alexandria are reported in some detail, but nothing is mentioned of Nizar's fate or that of Aftakin. ==Nizari schism==