He was born in 302/914 in Kairwan, the first Fatimid Imam to be born in Maghrib. His name was Ismail and kunya was Abu Tahir, surnamed al-Mansur bi-Amrillah (Victorious by the command of God). He acceded the throne on 334/945 during the time when Abu Yazid had laid a seige over Susa.
It may be known that kunya is a part of the Arab personal name, being an appellation consisting of Abu (father of) or Umm (mother of) and followed by a name, usually that of the bearer's eldest son.
Abu Yazid Khariji, or Abu Yazid Makhlad bin Kaydad, traced his tribal origin to the clan of Ifran, one of the leading branches of the Zanata. He was a schoolmaster at Taharat, and had a leaning towards the doctrines of the Kharijis. He learnt the doctrines from Abu Ammar al-A'ma. Abu Yazid had been elected then the leader of the Kharijis, and became more interested to acquire political power. After spending sometime in Taharat, he returned to Qastilia, where he started his anti-Fatimid agitation in 316/928 and soon procured a large following. With the Berbers moving quickly to his side, Abu Yazid engineered his revolt against the Fatimids in 332/944, and swiftly conquered almost all the southern regions, and seized Kairwan in 333/944. Abu Yazid advanced and laid a seige over Susa when al-Mansur ascended. Ibn Khallikan (1211-1282) writes in 'Wafayat al-A'yan' (1st. vol., p. 219) that, 'Al-Mansur was charged by his father (al-Qaim) to wage war against Abu Yazid, who had revolted against his authority. Abu Yazid Makhlad bin Kaidad belonged to the sect of Ibadites; he made an outward show of rigid devotion, but was in reality an enemy of God; he never rode but on an ass, nor wore any dress but woollen.'
The first task of al-Mansur was to relieve Susa. He himself commanded the forces and inflicted a severe defeat on Abu Yazid, and drove him back to Kairwan, then he went to Sabta. Al-Mansur reached Kairwan and helped the suffered people. Al-Mansur had been warmly received in Kairwan, and he also personally conducted a close chase, defeating Abu Yazid near Tubna and then around Masila. In 336/947, al-Mansur assisted by his general Ziri bin Manad, inflicted a final defeat on the Khariji Berbers in the mountains of Kiyana, where the rebels had entrenched themselves in a fortress, called Qalat Bani Hammad. According to Ibn Khallikan (1st Vol., p. 219), Abu Jafar al-Marwaruzi narrates the following anecdote: 'I went forth with al-Mansur on the day he defeated Abu Yazid, and as l accompanied him, he dropped from time to time one of the lances which he bore in his hand; so I picked it up and wiped it, and gave it to him, pronouncing it to be a good omen, and quoting to him the following verse:
`She threw away her staff, and a distant land became the place of her abode; (yet, she felt) as the traveller on his return, when his eyes are delighted (by the sight of home)'
On which, al-Mansur replied: 'Why did you not quote what is better and truer than that: `And We spoke by revelation to Moses, saying, `throw down thy rod'. And behold, it swallowed up that which they had caused falsely to appear. Wherefore the truth was confirmed, and that which they had wrought vanished. And they were overcome there, and were rendered contemptible' (7:114-116). To this I said: 'O, my Lord! you, who are the son of God's Apostle, utter that knowledge of which you are the sole possessor.'
Abu Yazid was suppressed and taken prisoner, but was died of his wounds. Jafar bin Mansur (d. 365/975) is the contemporary authority, who had also composed few poems about the revolt of Abu Yazid and the marvellous actions of al-Mansur. Ibn Athir (7th vol., p. 171) tells us that, 'Al-Mansur personally took charge of the military operations and put an end to Abu Yazid's menace. Had al-Mansur failed in checking this menace, it is probable that the Fatimid empire would not have survived long. With all this, al-Mansur behave generously with his implacable foe. He came to Kairwan in 334/945 and gave protection to the family of Abu Yazid who had despaired of life. He even granted his wives and children monthly allowances. He also granted Abu Yazid's request to restore his wives and children to him on condition that he would not wage war. But Abu Yazid soon broke his promise and tried to launch another insurrection.'
Fazal, the son of Abu Yazid continued the revolt in the Awras for a few months until he, too, was subdued and was brought to Mahdiya by Batit bin Ya'la bin Batit in 336/948. Other sons of Abu Yazid fled to Spain and took refuge under the Umayyads. The rebellion of Abu Yazid, however, had sucked away the resources of the state, forcing the Fatimids to pay a heavy price.
'The failure of Abu Yazid's rising,' writes H.U. Rahman in 'A Chronology of Islamic History' (London, 1989, p. 153), 'left the Fatimids far stronger than before and with a much firmer grip on the rein.'
When al-Mansur was subduing Abu Yazid's revolt, a report reached to him about a petty uprising of Hamid Bazaltain, the chief of the Maghrib, who had laid a siege over Tahrat soon after announcing his loyalty with the Umayyads of Spain. After crushing the revolt of Abu Yazid, al-Mansur focused his attention at the new rising, and himself commanded his army. He inflicted a defeat to Hamid and appointed Yala bin Muhammad, the chief of Banu Ifran in Maghrib.
Al-Mansur was unable to pay attention towards Sicily during the revolt of Abu Yazid, where Ibn Ataf was an inefficient governor. Taking advantage of his weakness, the Byzantines stopped the payment of the tribute to the Fatimids. In the meantime, the inhabitants of Sicily also rose against Ibn Ataf, who hid himself in the old castle of Palermo. Confronted by the chaotic situation caused by the rebellious at Palermo and Agrigento in Sicily against the Fatimid amirs, al-Mansur deemed it logical and sensible to entrust Sicily's administration to those whose fidelity was proven beyond doubt, and who, moreover, could maintain a neutral stand, therefore, al-Mansur appointed Hasan bin Ali al-Kalbi as the governor of Sicily in 336/946.
Hasan bin Ali al-Kalbi belonged to an influential Kalbid family, stemming from the tribe of Kalab bin Wabara of Banu Abil Hussain. Under the Aghlabids rule, the Kalabid family began to decline from public notice, but they became the main prop and stay during the Fatimids period, and swiftly found a milieu favourable to their rise, and became a governing element of Muslim Sicily by the middle of the 4th/10th century. Ali bin Ali al-Kalbi, one of the first dynasts of the family and son-in-law of Salim bin Abi Rashid, the then Fatimid governor of Sicily, from 305/917 to 325/936, died at the siege of Agrigento in 326/938. His son Hasan bin Ali al-Kalbi, who had distinguished himself in the campaigns waged by Imam al-Qaim and Imam al-Mansur against Abu Yazid, was the first of a succession of Kalbid governors in Sicily, a kind of hereditary emirate under the Fatimids which lasted until the middle of 5th/11th century.
In Sicily, Hasan bin Ali al-Kalbi finished the internal uprisings and restored peace. He also solidified his army, forcing the Byzantine emperor to resume the payment of the tribute to the Fatimids. On al-Mansur's death in 341/952, Hasan bin Ali returned to Mansuria, leaving behind the government of the island in the hands of his son, Ahmad bin Hasan (342-358/953-969), the second Kalbid governor of Sicily.
The new Fatimid policy led to the origination of the semi-independent dynasty of the Kalbids, which ruled over Sicily for almost a century on behalf of the Fatimids, having considerable autonomy. Hasan, called al-Samsan (431-445/1040-1053) was the last Kalbid governor of Sicily. The Norman Count Roger captured Messina in 1060, and Palermo, the capital of the island fell to them in 1072. The Normans also occupied Syracuse in 1085 and by 1091 the whole of the island came to the possession of the Normans. That was the end of the Muslim rule in Sicily.
The Kalbid era was one of the most prosperous periods in the history of Muslim Sicily. The island developed vital trade and played an important role in the transmission of Islamic culture into Europe. In Sicily, the schools, colleges, mosques and hospitals were also built, the agriculture was promoted and the new industries were set up. It is interesting to note that the medical institution of Palermo was far better than that of Baghdad and Cordova. According to 'Encyclopaedia of World Art' (Rome, 1958, 12th vol., p. 459), 'The oldest examples of silk weaving are from southern Italy, particularly Sicily, where the first looms were probably put into operation by the Saracens in the 9th century.'
The Fatimid art had certainly influenced the Italians through Sicily, and left behind many traces. A number of important pieces of gold and silver works, scattered in south Italy belonged to the Fatimids. The products of this workshop are characterized by a special technique of filigree work arranged in spirals or in vermiculated designs and by simply encased ornamented enamels in Fatimid style. According to 'Encyclopaedia of World Art' (Rome, 1958, 12th vol., p. 459), 'The influence of Fatimid art is seen in the two lions, each devouring a camel, that entirely cover the mantle of Roger II (1095-1154) almost as if it were half of an enormous orb. The lions are separated by a very stylized palmette. Also Fatimids are the palmettes decorating the edges of the sleeves and the hem of the dalmatic. To this were added the clearly Islamic motif of ornamental scripts - in this case, Naskhi letters, which flow elegantly to form a border.'
It may be noted that the magnetic instrument indicating the direction was known as qutb-numa (mariner compass), which came to be used by the navigators of the Mediterranean Sea, from Sicily to Alexandria for the first time. Idrisi (494-548/1100-1154), who compiled his geographical treatise in Sicily, however, is reported to have made an earliest description of the mariner compass. The Egyptians called it samia, because their terms were separate from those of the navigators of the high sea. It is beyond doubt that the Europeans were indebted to the Muslims for the mariner compass, which, they knew most probably after 5th century.
In 340/951, al-Mansur was reported that the emperor Constantine VII (913-959) of France was about to invade the Fatimid territories, thus a naval forces was dispatched under Faraj Saqali. Hasan bin Ali al-Kalbi, the governor of Sicly and Faraj jointly invaded Kaloria and defeated the French forces. The French emperor was obliged to send tributes and a peace-negotiating embassy to the Fatimid court. On their way back to Maghrib, the Fatimid naval forces conquered Reggio and built there a mosque, the ruins of which have been unearthed recently.
In 335/947, al-Mansur ordered yet another new capital built a short distance southwest of Kairwan, called Mansuria. It served a new Fatimid capital after Mahdiya.
Al-Mansur died in 341/952. F.Dachraoui writes in 'Encyclopaedia of Islam' (1990. 6th vol., p. 434) that, 'Mansur's personality shines with an unparalleled brilliance under the pens of the Ismaili authors, who, as also the Sunni chroniclers, show great wander in relating his exalted deeds and who dwell at length on giving accounts of the battles, rebellions and other bloody events. According to their accounts, he possessed only good qualities: he was generous and benevolent, level-headed and perspicacious, above all possessing a brilliant eloquence; since his youth, he had devoted himself to piety and study, and was deeply conscious of his high calling as impeccable Imam and of his grandeur as a monarch.'