Yet it was as impossible for the Almohades to retain their fanaticism as it had proved for their predecessors. When, in 1228, on the deposition of the Almohad Miramamolin Al-Abdel, his nephew Yahia was raised to the throne, his brother Al-Memon-Abo-l-Ola, who was in Spain, claimed the succession. To obtain the assistance of San Fernando III, who lent him twelve thousand Christian troops, he agreed to surrender ten frontier strongholds, to permit the erection of a Christian church in Morocco, where the Christians should celebrate publicly with ringing of bells, and to allow freedom of conversion from Islam to Christianity, with prohibition of the converse. This led to the foundation of an episcopate of Morocco, of which the first bishop was Fray Aguelo, succeeded by Fray Lope, both Franciscans.[141] Co-operation of this kind with the Christians meets us at every step in the annals of the Spanish Saracens. Aben-al-Ahmar, who founded the last dynasty of Granada, agreed to become a vassal of San Fernando III, to pay him a tribute of 150,000 doblas per annum, to furnish a certain number of troops whenever called upon, and to appear in the Córtes when summoned, like any other ricohome. He aided Fernando greatly in the capture of Seville, and, in the solemnities which followed the entry into the city, Fernando bestowed knighthood on him and granted him the bearing of the Castilian guidon--gules, a band or, with two serpents, and two crowned lions as supporters--a cognizance still to be seen in the Alhambra.[142] * * * * *