A large-scale Berber uprising erupted in the far western Maghreb, fueled in part by Kharijite preaching and resentment of Umayyad governance. The revolt destabilized Umayyad authority in North Africa and exposed the regime’s growing difficulties in managing its far-flung provinces—an important backdrop to the wider crisis of the 740s.
In fighting associated with the Berber Revolt, a major Berber victory inflicted severe losses on Arab/Umayyad elites. The defeat worsened the strategic position of the Umayyad state in the western Islamic world and further strained imperial cohesion during the decade preceding the Abbasid breakthrough.
The killing of Caliph al-Walid II intensified intra-Umayyad conflict and helped ignite the Third Fitna (a period of civil war and fragmentation). The weakening of central authority in Syria and Iraq created political openings that the Abbasid movement would soon exploit.
Marwan II took power amid the Third Fitna and attempted to restore Umayyad control. Despite military and administrative efforts, his reign was consumed by internal strife and the mounting Abbasid challenge in the east.
In Khurasan, Abu Muslim publicly raised the Abbasid movement’s black banners, transforming clandestine organization into open rebellion. This marked the effective start of the military phase of the Abbasid Revolution and shifted the contest decisively toward armed struggle.
Abu Muslim’s forces took control of Merv, expelling Umayyad authority from a key provincial capital. Control of Merv provided the Abbasids with a major administrative and logistical base for further westward campaigning.
Under the Abbasid commander Qahtaba ibn Shabib, revolutionary forces pushed west across Iran, winning battles and bringing the conflict into the heartlands of the caliphate. This campaign linked Khurasani military power to Iraqi opposition networks.
The Abbasid family’s leader, Ibrahim al-Imam, died while imprisoned by the Umayyads. His death accelerated the transfer of leadership to his brother Abu al-‘Abbas al-Saffah, as the revolution’s armies were entering Iraq.
After setbacks near Kufa, the Umayyad governor Ibn Hubayra withdrew to Wasit, which the Abbasids besieged for roughly eleven months. The siege tied down major Umayyad forces in Iraq while Abbasid armies moved to finish the struggle elsewhere.
Abbasid-aligned forces secured Kufa, and Abu al-‘Abbas was proclaimed caliph there in October 749. Kufa’s capture gave the Abbasids a powerful political-religious center in Iraq and a platform to claim legitimate caliphal authority.
Abbasid forces decisively defeated Caliph Marwan II near the Great Zab River. The battle effectively ended Umayyad control of the caliphate’s core territories and opened the road to the capture of Syria.
Following the Great Zab defeat, Abbasid forces moved into Syria and took Damascus, long the Umayyad capital. The fall of Damascus symbolized the transfer of imperial power away from the Umayyad Syrian base toward the new Abbasid regime centered in Iraq.
The Umayyad garrison at Wasit capitulated in mid-750, eliminating the last substantial Umayyad military stronghold in Iraq. With Iraq and Syria secured, Abbasid authority over the central provinces became decisive.
Marwan II was killed while fleeing into Egypt, marking the final collapse of Umayyad caliphal power. The Abbasids consolidated rule afterward, while surviving Umayyad elements would later reconstitute power in al-Andalus (Spain) in a separate polity.
The Abbasid Revolution and the Fall of the Umayyad Caliphate (740–750)
