Ma'mun, al-

Ma'mun, al-

(born 786, Baghdad, Iraq—died August 833, Tarsus, Cilicia) Seventh caliph (r. 813–833) of the 'Abbasid dynasty. He was the son of the celebrated Harun al-Rashid and after his father's death (809) defeated his brother al-Amin in a civil war (813) to assume the caliphate. Attempting to reconcile Sunnite and Shi'ite Muslims, he designated as his heir a Shi'ite, 'Ali al-Rida, which failed to satisfy Shi'ite extremists and angered Sunnites. In any event, al-Ma'mun was predeceased by his heir. He became a supporter of the Mu'tazilites, a theological school whose opinions on such issues as the nature of God and man's free will were at variance with accepted doctrine and found little popular support. His sponsorship of translations of Greek philosophical and scientific works and his building of observatories and libraries proved a more lasting legacy.