. . . "Fourth Muslim Civil War" . . . . "Al-Amin's succession was contested" . . "the civil war" . "conflict" . . "fourth fitna civil war" . . "Great Abbasid Civil War" . . "unrest" . . "Abbasid Civil War" . "vicious civil war" . . "fourth civil war" . "al-Amin's forces" . . "tumultuous period" . . "War Between Brothers" . . "Fourth Fitna" . . . . . "great Abbasid civil war" . . . . "reconquest of Egypt" . "subsequent civil war" . "anarchy that engulfed Syria" . "civil war between" . "civil war of 811\u2013813" . . . . "Fourth Fitna" . . "Fourth Civil War" . . "Local rulers & rebel leaders" . "al-Ma'mun's forces" . . "civil war between Amin and Ma'mun" . . . . "civil war" . "civil war that erupted after Harun's death" . "Defeat and death ofal-Amin;al-Ma'munis recognized as Caliph on 27 September813." . "Abbasid civil war" . . . .