Imam al-Mansur Billah (AS) — The Vanquisher of Abu Yazid

The Imam Who Saved the Fatimid Dynasty

Sayyidna al-Mansur Billah (المَنصُورُ بِاللَّه — the Victorious through Allah) was the 15th Imam in the Ismaili Tayyibi chain and the 3rd Caliph of the Fatimid dynasty. He ruled from 334–341 AH / 946–953 CE — a relatively brief reign of seven years, but one that determined the survival of everything the Fatimids had built.

Al-Mansur is remembered above all for one achievement: the final defeat of Abu Yazid al-Kharijite, the “Man of the Donkey,” whose revolt had come within a city wall’s width of destroying the Fatimid Caliphate.

Background — The Revolt His Father Faced

When al-Mansur became Imam on the death of his father Imam al-Qa’im (AS) in 334 AH, he inherited a state in crisis:

• Abu Yazid — the Kharijite rebel who had swept across North Africa — had besieged the Fatimid capital al-Mahdiyya
• Imam al-Qa’im had died during the siege
• The Fatimid court was trapped inside the fortified coastal city

One of al-Qa’im’s final acts had been to keep his death secret so the defenders would not lose heart — and to transmit the nass of the Imamate to al-Mansur in private. It was al-Mansur who now had to save the dynasty.

The Final Campaign Against Abu Yazid

Al-Mansur reversed the momentum against Abu Yazid through a combination of:

Defensive consolidation: He held al-Mahdiyya and organized the remaining Fatimid forces.

Strategic patience: Rather than rushing into battle, al-Mansur allowed Abu Yazid’s coalition — which relied on Berber tribal loyalties that were difficult to maintain over long sieges — to begin fragmenting.

Decisive offensive: When the moment came, al-Mansur launched a decisive military campaign westward. Battle by battle, city by city, the Fatimid forces recaptured what had been lost.

Abu Yazid was forced to retreat. The retreat became a rout. In 336 AH / 947 CE, after years of warfare, Abu Yazid was captured while attempting to flee into a mountain stronghold. He died of wounds shortly after capture.

The victory was total. The Fatimid Caliphate, which had seemed on the verge of destruction, was safe.

The City of al-Mansuriyya

To commemorate the final victory over Abu Yazid, al-Mansur founded a new city near Kairouan: al-Mansuriyya (City of Victory). This became the new Fatimid capital in North Africa, replacing the more defensible but isolated al-Mahdiyya.

Al-Mansuriyya was a planned city built in the circular style favored by Abbasid Baghdad — a statement of Fatimid civilizational ambition. It served as the Fatimid capital until the conquest of Egypt and the founding of Cairo under his son al-Mu’izz.

Succession to al-Mu’izz

Al-Mansur (AS) died in 341 AH / 953 CE and was succeeded by his son Imam al-Mu’izz li-Din Allah (AS) — the 16th Imam who would go on to conquer Egypt, found Cairo, and build al-Azhar. Al-Mansur had received the nass from his father and transmitted it to al-Mu’izz — the continuation of the chain.

His Place in the Imam Chain

See also: Imam al-Qa’im, Imam al-Mu’izz, Fatimid Caliphate