Almohad Caliph from 1229 to 1232
Abu al-Ala Idris al-Ma'mun (; "Abū Al-`lā Al-Mā'mūn Idrīs ibn Al-Manṣūr"; died 16 or 17 October 1232) was an Almohad rival caliph who reigned in part of the empire from 1229 until his death. He was a son of Abu Yusuf Yaqub al-Mansur and brother of Muhammad al-Nasir and Abdallah al-Adil. 
Life.
Al-Ma'mun was the first Almohad ruler to officially renegade on the Imamate of the Mahdi Ibn Tumart, recognizing instead the Abbasid caliph in Baghdad as Imam and reverted back to promoting the Taqlid of the Maliki madhab formerly promoted by the Almoravids whom the Almohads had ousted less than a century earlier. He claimed instead that the title Mahdi applied to Jesus. His nephew Yahya took this step as license to proclaim himself caliph and a civil war broke out. At the same time, a revolt took place in Murcia under emir al-Mutawakkil. Al-Ma'mun therefore send his relative Abu Zayd from Valencia to Murcia to squash the revolt, but Abu Zayd was defeated. Al-Ma'mun then went with an army to confront al-Mutawakkil, but he could not capture the city itself. As the situation in North Africa also became worse, al-Ma'mun departed to Morocco and ended thus Almohad rule on the peninsula.
Idris asked Ferdinand III of Castile for help, receiving 12,000 knights who allowed him to conquer that city and to massacre the sheikhs that had supported Yahya. Following his victory, Idris honored the treaty with Ferdinand III and allowed the construction of a Christian church in Marrakesh in 1230, which was destroyed two years later by Yahya. The side changes of Idris soon lost him popular consent. In the early 1232, when he was besieging Ceuta, Yahya took the occasion to capture Marrakesh. Idris died during the march to reach the city, and was succeeded by his son Abd al-Wahid II.
The rejection of typical Almohad doctrine also caused the break away of the Hafsid dynasty in the Ifriqiya province. 
One of his consort was a Christian woman, Habbaba, who upon his death informed the Christian palace militia before she informed the Muslim members of the court, giving the former an advantage. 
Idris’ other son was Abu al-Hasan as-Said al-Mutadid.
References.
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