 Complete the following phrase:  Abu al-Abbas Abdallah ibn Harun al-Rashid ; 14 September 786  9 August 833, better known by his regnal name al-Mamun , was the seventh Abbasid caliph, who reigned from 813 until his death in 833. He succeeded his half-brother al-Amin after a civil war, during which the cohesion of the Abbasid Caliphate was weakened by rebellions and the rise of local strongmen; much of his domestic reign was consumed in pacification campaigns. Well educated and with a considerable interest in scholarship, al-Mamun promoted the Translation Movement, the flowering of learning and the sciences in Baghdad, and the publishing of al-Khwarizmis book now known as Algebra. He is also known for supporting the doctrine of Mutazilism and for imprisoning Imam Ahmad ibn Hanbal, the rise of religious persecution mihna, and for the resumption of 