Abu Mansur al-Nizar, surnamed al-Mustapha al-dinillah (the chosen for God's religion), was born in Cairo on 437/1045. He assumed the Imamate on 18th Zilhaja, 487/January 6, 1095 at the age of 50 years. He had been however proclaimed as a successor in 480/1087 before the notables in the court by his father. His participation in state affairs is scant. In 454/1062, during the perilous period of Egypt, al-Mustansir had however sent him to the port of Damietta with the Fatimid army to execute few assignments.
One remark at least should not be omitted that Nizar is a Persian word, and according to "Persian-English Dictionary" (London, 1892, p. 1396) by F. Steingass, it means thin, slim, slender, lean, spare or weak. As it is said "kilki nizar" means "a slender reed or pen." The Iranian name given to the elder son by Imam al-Mustansir billah tends to the fact that he had perceived the forthcoming bifurcation in the Ismailis, and that his real successor would be supported in the Iranian society than in the Arabian. It therefore seems that al- Mustansir had chosen the name Nizar to cohere him and his descendants with the Iranian culture. It may also be noted that the cause of the Nizarid was supported by the Iranian missionaries, notably Hasan bin Sabbah, Nasir Khusaro, Abdul Malik bin Attash etc.
We have seen that Imam al-Mustansir ascended at the age of seven years in 427/1036, therefore, the state was governed by his mother. The Fatimid vizir, Ali bin Ahmad Jarjarai was an able administrator, who died in 436/1044. He was subsequently followed by Ibn al-Anbari and Abu Mansur Sadaqa, but none of them proved successful. In 442/1050, Abu Muhammad Hasan bin Abdur Rehman Yazuri became the vizir for eight years. He was a great reformer, but died in 450/1058. Hence, about 40 new vizirs had been installed during the next 15 years (450- 466/1058-1074), but none among them was so capable to administer the state affairs. Finally, al-Mustansir invited an Armenian, called Badr al-Jamali, who reached Cairo in 466/1074 with his Armenian troops, and took charge of the Fatimid vizirate. He efficiently dealt the state affairs and restored peace.
When Hasan bin Sabbah was yet in Cairo in 471/1078, De Lacy O'Leary writes in "A Short History of the Fatimid Khalifate" (London, 1923, p. 209) that, "At the time, it appears, the court was divided into two factions over the question of the succession, the one party holding to the Khalif's elder son Nizar, the other to a younger son named Musta'li. In one place Nasir-i Khusaro says that the Khalif told him that his elder son Nizar was to be his heir, and the succession of the older son would be in accordance with the doctrines of the sect as already proved by their adherence to Ismail, the son of Jafar as-Sadiq. But Badr and the chief officials were on the side of the younger son Musta'li."
Badr al-Jamali thus expected the succession of Musta'li but he died in 487/1095, a month before the death of Imam al-Mustansir. The latter appointed Lawun Amin ad-Dawla as a new vizir, but after few days, al-Afdal, the son of Badr al-Jamali managed to obtain office of vizirate when the Imam was almost on death-bed, and also became amir al-juyush (commander of the army). After the death of al-Mustansir, the year 487/1095 marks the triumph of vizirial prerogative over caliphal authority in the structure of the Fatimid empire. Al-Afdal however, was fearing of being deposed by Nizar, so he conspired to remove him. There is one other story purporting his enmity with Nizar. If the story quoted by Charles Francois Defremery (1822-1883) in "Histoire des Ismaeliens ou Batiniens de la Perse" (JA, ser. 5, XV, 1860, p. 154), is genuine, it illustrates how a little, rather a trifling thing determines great events. Al-Afdal, so the account goes, was once mounted on his horse in the passage leading from the golden gate to the entrance of the palace when Nizar passed by. Al- Afdal did not dismount to honour the Prince according to the royal custom. Nizar called out, "Get down from your horse, O'Armenian slave! How impolite you are?" Dr. Zahid Ali is of an opinion that it was a bone of contention and since that day, al-Afdal became an enemy of Nizar, vide "Tarikh-i Fatimiyyin Misr" (Karachi, 1963, p. 294). In sum, Nizar fell a victim to the jealousy of al-Afdal.
Makrizi also quotes the above incident, vide "Itti'az" (3rd vol., p. 12). It must be remembered that the phrases al-adab fil salam and adab al-khidma designated in the broadest sense in the protocol (adab) to be observed in the Fatimid court. It was the custom for the vizirs to ride into the palace through the golden gate (bab al-dhahab) and dismount at a designated spot, called "the passage of the vizirate" (maqta al-vizara), but al-Afdal exceeded the limit and treated impolitely with al-Nizar.
Aiming to retain the power of the state in his own hands, al-Afdal favoured the candidacy of al-Mustansir's youngest son, Abul Kassim Ahmad, surnamed Musta'li, who would entirely depend upon him. Al-Musta'li was about 20 years old, and already married to al-Afdal's daughter. Al-Afdal moved swiftly, and on the day following al-Mustansir's death, he placed the young prince on the throne with the title of al-Musta'li-billah. He quickly obtained for al-Musta'li the allegiance of the notables of the court. He also took favour of al- Mustansir's sister, who was prepared to declare a fabricated story that al-Mustansir had changed the nass in favour of Musta'li at very last hour in presence of the qadi of Egypt, but the cause of change of nass was not given at all. Marshall Hodgson writes in "The Order of Assassins" (Netherland, 1955, p. 63) that, "Nizar's right to the Egyptian succession by sectarian principles was very strong. The Sunni historians assume him to have been designated heir-apparent. This "first nass" would clearly give him claim to Ismaili allegiance against any later nominee on the analogy of Ismail himself, whose claim could not be set aside for his brother Musa."
The Egyptian historian, Nuwayri (677-732/1279-1332) writes in "Nihayat al-Arab" that, "When al-Mustansir billah died, his son al-Nizar, who was the wali'l-ahd, took his seat on the throne and desired homage to be done to himself; but al-Afdal refused, through dislike to al-Nizar, and he had a meeting with a member of amirs and men of rank, to whom he said, that Nizar was come to the age of manhood, and they could not hope to escape his severity; so the best thing to be done was to do homage to his youngest brother Musta'li. This plan was approved of by all except Muhammad Ibn Massal al-Maliki". The extant sources recount that al-Afdal hastened to proclaim Musta'li and on the next day, al-Afdal sent for the other sons of al-Mustansir, biding them to come quickly. Al-Nizar and his brothers, Abdullah and Ismail as soon as entered the palace, and saw the younger brother seated on the throne, at which they were filled with indignation. Nuwayri writes in "Nihayat al-Arab" that al-Afdal said to them: "Go forward and kiss the earth in the presence of God and of our lord al-Must'ali billah! Do him homage, for it is he whom the Imam al-Mustansir billah has declared as his successor to the caliphate." To this al-Nizar answered: "I would rather be cut in pieces than do homage to one younger than myself, and moreover I possess a document in the handwriting of my father by which he names me successor, and I shall go and bring it." He, thus withdrew from the court in haste.
It implies that al-Nizar and his brothers were summoned in the palace under usual manner. He must have brought the written document with him, had he known the enthronment of Must'ali. Another outstanding feature of Musta'li was that he was silent on the whole, and himself did not ask his brothers to pay him homage. It was only al-Afdal to deal the proceeding all alone. Musta'li was planned to enthrone with the firm hold of the vizir. According to "Religion in the Middle East" (London, 1969, 2nd vol., p. 321) ed. by A.J. Arberry, "Both Ibn al-Athir and Ibn Khaldun agree that Nizar was the duly appointed heir apparent whose claims were overlooked by the energy and diplomacy of al-Afdal."