Abu Tahir Isma'il (; January 914 – 18 March 953), better known by his regnal name al-Mansur Billah (), was the thirteenth Isma'ili imam and third caliph of the Fatimid Caliphate in Ifriqiya, ruling from 946 until his death. He succeeded his father, al-Qa'im, after the latter's death, in what was likely a bloodless palace coup. At the time of al-Mansur's accession, most of the Fatimid mainland realm in Ifriqiya had been lost to a large-scale anti-Fatimid revolt led by the Kharijite preacher Abu Yazid, who was laying siege to al-Qa'im's fortified coastal palace city of al-Mahdiya. Unlike his father he was an active and publicly visible monarch, but plagued by illness, which led to his early death.
Al-Mansur immediately took up the fight against the revolt with considerable energy, but kept his father's death secret until after the final suppression of the rebellion, governing instead as the ostensible designated successor and "Sword of the Imam". Leaving the trusted eunuch chamberlain Jawdhar to run the government in his stead, al-Mansur took to the field in person, leading the Fatimid army to victory over the rebel army outside Kairouan, and pursuing its remnants into the Hodna Mountains. After a long pursuit, Abu Yazid was finally cornered and captured, before dying of his injuries on 19 August 947. After Abu Yazid's death, al-Mansur publicly proclaimed his caliphate. His victory over Abu Yazid was celebrated as a triumph over a 'False Messiah', and as heralding a new beginning for the dynasty and its divine mission. Al-Mansur spent the remainder of his reign in al-Mansuriya, a new capital city he founded in 948. During his reign, he also secured the allegiance of the Sanhaja Berbers under Ziri ibn Manad, recaptured Tahert from the rebellious Miknasa Berbers, suppressed a revolt in the overseas Fatimid province of Sicily, launched naval raids against Byzantine holdings in southern Italy, and engaged in a mounting antagonism with the rival Umayyad state of Córdoba.
Early life and accession The future al-Mansur was born Isma'il, in early January 914, in the palace city of Raqqada near Kairouan. He was the son of the then heir-apparent and future second Fatimid imam–caliph, Muhammad al-Qa'im bi-Amr Allah (), and a local slave concubine, Karima, who had once belonged to the last Aghlabid emir of Ifriqiya, Ziyadat Allah III. Isma'il was not the oldest son of al-Qa'im, but the firstborn, al-Qasim, reportedly predeceased his father.
According to the official version of events, on 12 April 946, al-Qa'im publicly proclaimed Isma'il as his heir, with the regnal name of al-Mansur Billah, and when he died on 17 May, al-Mansur became imam and caliph. Modern historians of the Fatimid period, such as Heinz Halm and Michael Brett, suspect that al-Mansur's rise to power was the result of a palace intrigue headed by the influential slave chamberlain Jawdhar, with the participation of other figures from al-Qa'im's harem. His mother, Karima, and his wet nurse, Salaf, are known to have aided him in his power struggle against his half-brothers, and are described as one of few women to have participated in political affairs.El-Azhari, Taef. Queens, Eunuchs and Concubines in Islamic History, 661–1257. Edinburgh University Press, 2019 Several factors suggest this: given al-Qa'im's debilitating illness, it is unclear whether he was at all capable of proclaiming a successor; the first act of the new caliph was to confine his uncles and brothers to house arrest in the palace, under the supervision of Jawdhar; Jawdhar, in his memoirs, claims that Isma'il had been secretly nominated as father's heir already at the time of al-Qa'im's own accession in 934, with Jawdhar himself being the only one entrusted his secret; and al-Mansur himself was apparently obliged to compose a tract defending his succession, which points to the contested nature of his accession.
Reign Suppression of the rebellion of Abu Yazid At the time of his accession, the Fatimid Caliphate was undergoing one of its most critical moments: a large-scale rebellion under the Kharijite Berber preacher Abu Yazid had overrun Ifriqiya and was threatening the capital al-Mahdiya itself. As a result, in the words of the historian Farhat Dachraoui, "[al-Mansur] had to face up to, immediately, the heaviest responsibilities without having served any apprenticeship as ruler". Al-Mansur would prove up to the task: both Isma'ili (pro-Fatimid) and Sunni (anti-Fatimid) sources agree that al-Mansur was an exemplary ruler, praising both his erudition and eloquence in Classical Arabic as well as his bravery and energetic leadership in battle.
While the revolt of Abu Yazid lasted, al-Mansur and his government kept the death of his father secret. All public business and ceremonies were still conducted in al-Qa'im's name, and Isma'il acted ostensibly only as his designated heir. Indeed, the regnal name of al-Mansur was only publicly assumed after the final suppression of the uprising. Nevertheless, the new ruler quickly showed his ability. Already before his father's death, on 16 May, he sent by sea weapons and supplies to the besieged city of Sousse, and within days launched a coordinated attack to relieve the city: on 26 May, the garrison of Sousse, assisted by Kutama Berber cavalry from the south and troops landed by sea from the north, broke the siege and forced Abu Yazid to withdraw his forces inland, towards Kairouan.
Battle for Kairouan Abu Yazid found Kairouan in rebellion against him and the city gates closed, so that he established a camp two days' march from the city. In the meantime, al-Mansur had met with a delegation of Kairouan notables at Sousse, and issued a full amnesty in return for their renewed loyalty. On 28 May, the caliph's proclamation was read in the city, and on the same day the Fatimid army, headed by the caliph himself, set up camp south of the city. The Fatimid prince was forced to lead by example to convince the unruly Kutama to fortify the camp with a ditch and wall, since the Berbers considered this a sign of cowardice and regarded digging as slaves' work. Only after al-Mansur himself took the spade and began digging were they persuaded to help.
This proved fortunate, as Abu Yazid attacked the camp on the morning of 5 June, and was only thrown back with great difficulty. According to an eyewitness account, al-Mansur played a leading role in repelling the attack, his ceremonial parasol conspicuously displayed and serving as a rallying point, but it is possible that his role has been embellished to further legitimize his position. The two armies remained entrenched around Kairouan for the next two months, engaging in frequent clashes. Abu Yazid tried several times to take the city gates by assault, but al-Mansur had established smaller fortified camps to protect them. Abu Yazid tried to force the Fatimids to withdraw by sending his son to raid the environs of al-Mahdiya, where many of the Kutama had settled their families; but although al-Mansur sent some troops to shield them, he refused to move his main army.
While al-Mansur was slowly building up his numerically inferior forces with contingents from the remote provinces of the Fatimid empire, Abu Yazid's support began to dwindle, and his followers abandoned his camp. Only the Hawwara and Banu Kamlan Berbers remained steadfastly loyal to him. With increasing confidence, al-Mansur marched his army out to provoke a pitched battle, but Abu Yazid refused the challenge. Finally, on 13 August the Fatimids stormed the rebel camp, and Abu Yazid's troops broke and fled. The victory proved doubly fortuitous for al-Mansur. Seeking support against the Fatimids, Abu Yazid had made contact with the Spanish Umayyads and recognized the suzerainty of the Umayyad caliph Abd al-Rahman III. An Umayyad fleet had been dispatched to assist him, but when its commander heard news of the Fatimid victory at Kairouan, he turned back.
Even in his victory dispatch to the capital, read out by the chamberlain Jawdhar, al-Mansur upheld the fiction of the still living al-Qa'im, describing himself merely as the "Sword of the Imam". The Fatimid ruler set about achieving a reconciliation with the citizens of Kairouan: he abstained from re-appointing an Isma'ili over the city, instead choosing the old and respected Malikite jurist Muhammad ibn Abi'l-Manzur; he did not appoint a Kutama as governor, but a military officer of Slavic origin, Qudam al-Fata; he remitted all taxes for two years; and offered much of the captured booty as alms to the city poor. At the same time, al-Mansur ordered that the site of his camp south of the city be made into a new palace city, known officially as al-Mansuriya and locally as Sabra. Aside from thus immortalizing his victory, the prospect of the caliphal residence returning to the vicinity of Kairouan, the old capital of Ifriqiya, was another sign of caliphal favour to the Kairouanese. While at Kairouan, on 18 October al-Mansur received an envoy of the Byzantine Empire. It is unknown what the envoy's business with the Caliph was, but it most likely concerned the renewal of a truce that was in effect in southern Italy, which suited both powers at the time.
Pursuit of Abu Yazid While al-Mansur remained at Kairouan, in the north al-Hasan ibn Ali al-Kalbi had gathered fresh Kutama forces at Constantine and recaptured Béja and Tunis, securing the caliph's northern flank. Reinforced with a thousand cavalry from the Cyrenaica, al-Mansur set out from Kairouan on 24 October in the direction of Sbiba. From there the Fatimid army marched to Bajaya, which had resisted the rebels' attacks, and welcomed the Fatimid troops as liberators. Ibn Khazar, the leader of the Zenata Berbers, sent an envoy to declare his allegiance to al-Mansur. This in turn forced Abu Yazid to flee to the south and bypass the Zenata territories through the desert. Al-Mansur followed him until Biskra, but the local guides counseled against following the rebel leader, as the route was dangerous for an army. At Biskra, the governor of Msila and the Zab region, Ja'far ibn Ali ibn Hamdun, presented himself to the caliph in submission, bringing with him a youth who was being hailed as a prophet in the Aurès region. After parading him through the camp, al-Mansur had the youth skinned alive and stuffed.
When the caliph learned that Abu Yazid had found refuge in the Jabal Salat mountains, west of the Chott el Hodna lake, he led his army north to Tubna and then west, along the northern shore of Chott el Hodna. Abu Yazid confronted the Fatimid army at the town of Magra on 9 December, but was defeated. Following the victory, delegations from the tribes and settlements of the region began arriving at Msila to declare their loyalty to al-Mansur, including Ibn Khazar's son, Ya'qub. Shortly after, Abu Yazid launched an attack on al-Mansur's army camp near Msila, but was again beaten back. Al-Mansur sent his troops into the Hodna Mountains to pursue the rebel, but Abu Yazid again fled to the Jabal Salat. When the Fatimid troops pursued him there, he again fled to the desert, and this time al-Mansur was determined to follow him. After a grueling eleven-day march in the desert he was forced to turn back, only for the heavy winter to take further toll on his army.