The son of Al-Rashid of "The Arabian Nights" and a great grandson of Al-Mansur, founder of Baghdad and the architect of the Abbasid state, Al-Mu'tasim was destined to succeed to the caliphate. Inheriting a troubled and fragmented empire, Al-Mu'tasim was to be the last caliph of the illustrious Abbasid dynasty, which could be traced to Abbas, the Prophet Muhammed's uncle, to exercise such absolute - and inherited - power. Following his reign the power of the caliph dwindled as various military generals gained the ascendancy. After civil war between Al-Mu'tasim's brothers Al-Amin and Al-Ma'mun divided the caliphate into two, Al-Ma'mun's policy of doctrinal intolerance shook the foundations of the Abbasid Caliphate and further weakened the state. Thus coming to power during a critical period, Al-Mu'tasim also had to contend with serious rebellion at home and a growing threat from Byzantium. His reign was, perhaps inevitably, a military one, and his widely-acknowledged valour and genius as a commander stood him in good stead. His garrison capital, Samarra, on the banks of the Tigris in present-day Iraq, is now a pilgrimage destination for many.