Humanities › History & Culture Abu Ja'far al Mansur Share Flipboard Email Print Public Domain History & Culture Medieval & Renaissance History People & Events Daily Life American History African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Military History The 20th Century Women's History View More By Melissa Snell History Expert B.A., History, University of Texas at Austin Melissa Snell is a historical researcher and writer specializing in the Middle Ages and the Renaissance. She authored the forward for "The Complete Idiot's Guide to the Crusades." our editorial process Melissa Snell Updated March 05, 2019 Abu Ja'far al Mansur was noted for establishing the Abbasid caliphate. Though he was actually the second Abbasid caliph, he succeeded his brother only five years after the overthrow of the Umayyads, and the bulk of the work was in his hands. Thus, he is sometimes considered the true founder of the Abbasid dynasty. Al Mansur established his capital at Baghdad, which he named the City of Peace. Quick Facts Also known as: Abu Ja'far Abd Allah Al-mans ur Ibn Muhammad, al Mansur or Al Mans urOccupation: CaliphPlaces of residence and influence: Asia and ArabiaDied: Oct. 7, 775 Rise to Power Al Mansur's father Muhammad was a prominent member of the Abbasid family and the great-grandson of the revered Abbas; his mother was an enslaved Berber. His brothers led the Abbasid family while the Umayyads were still in power. The elder, Ibrahim, was arrested by the last Umayyad caliph and the family fled to Kufah, in Iraq. There al Mansur's other brother, Abu nal-Abbas as-Saffah, received the allegiance of Khorasanian rebels, and they overthrew the Umayyads. Al Mansur was firmly involved in the rebellion and played an important role in eliminating the remains of Umayyad resistance. Only five years after their victory, as-Saffah died, and al Mansur became caliph. He was ruthless to his enemies and not altogether trustworthy to his allies. He put down several revolts, eliminated most of the members of the movement that brought the Abbasids to power, and even had the man who helped him become caliph, Abu Muslim, killed. Al Mansur's extreme measures caused difficulties, but ultimately they helped him to establish the Abbasid dynasty as a power to be reckoned with. Achievements But the most significant and long-lasting achievement of al Mansur is the establishment of his capital at the brand new city of Baghdad, which he called the City of Peace. A new city removed his people from troubles in partisan regions and housed an expanding bureaucracy. He also made arrangements for succession to the caliphate, and every Abbasid caliph was directly descended from al Mansur. Al Mansur died while on a pilgrimage to Mecca and is buried outside the city.