Abstract : In 1147, the first Almohad imâm-caliph, Abd al-Mu’min, captured Marrakech, bringing an end to the reign of the Sanhâja, after a long struggle lasting seven years. The following year, in Mâssa, a ribât situated to the south of Marrakech, a serious uprising broke out led by Ibn Hûd al- Mâssî. According to the Almohad chronicles, people fleeing from different regions flocked together under his banner. He was proclaimed mahdî by the inhabitants of Sijilmâssa and of Dara, the Dukkâla, the Regraga, the Huwwâra and the Tâmesna. The Caliph had great trouble in putting down this rebellion. Often regarded as the « recognition » (itirâf) of Almohad power, in fact it was a bloody purge, which also involved the Almohad hierarchy, responsible for « pacifying » the different regions of the Empire : the Almohad chronicler, al-Baydhaq, quotes a figure of 32,780 executions! In spite of occasional small victories, Ibn Hûd al-Mâssî was finally defeated and killed in 1149. Only Marrakech and Fez did not take part in what Almohad chroniclers of this period described as a ridda, so recalling the Wars of Apostasy against rebel Arab tribes that broke out on the death of the Prophet Muhammad. Why was Fez, one of the great historic capitals of Morocco, if not the greatest, not rewarded for its loyalty? In the end, the Almohads chose Marrakech, an Almoravid foundation, as their capital and themselves founded Ribât al-Fath, the town that would later become Rabat. Their fate is therefore linked to Fez’s two main rivals, Marrakech in the Mediaeval and Early Modern period, and Rabat the present-day capital. An analysis of the origin of the Almohads and the history of their Empire will perhaps shed light on why they made these choices.