Abbasid Caliph. He succeeded his brother Abul Abbas in the 754. He did kill Abdallah, his uncle, and Abu Muslim, general of his troops. He fought against the Greeks, against the Umayyads and Shia partisans of Ali. He founded the city of Baghdad at the site of the ancient Persian Ctesiphon. He could not help that the last surviving Umayyad, Abd al - Rahman, initiated a Caliphate in the Iberian peninsula. On his death, in the 775, his son al - Mahdi succeeded him. (See Caliphate).