Ibrahim ibn al-Ashtar, Mukhtar's governor over Mosul and its dependencies, i.e. the Jazira (Upper Mesopotamia), Adharbayjan, and Arminiya, afterward defected to Mus'ab.
[4][5] Based on the description of the 13th-century geographer Yaqut al-Hamawi, historian Michael Fishbein locates it roughly 3 kilometers (1.9 mi) south of Kufa.
Historian Laura Veccia Vaglieri concludes that this meant "the hydrographic system of the region had thus probably undergone a transformation".
Mus'ab summoned his most experienced commander, Muhallab ibn Abi Sufra, who had been engaged in battles against the Kharijites, and launched the offensive against Kufa.
[14] At the time, relations were strained between Mukhtar and his strong-man Ibrahim ibn al-Ashtar, who was posted in Mosul in the eastern Jazira (Upper Mesopotamia).
On learning this, Mukhtar fortified the palace, stocked provisions, and placed Kufa under the command of a certain Abd Allah ibn Shaddad.
Then he went to al-Saylahin, a place between al-Hirah and al-Qadisiyya,[6] and dammed the Euphrates so that its waters were redirected to fill the canals leading to al-Hirah and al-Qadisiyya, thereby leaving Mus'ab's river boats stuck in mud; these troops disembarked and marched on foot, while Mus'ab and his horsemen destroyed the dam and continued toward Kufa.
[25] When the armies neared each other, Mukhtar sent detachments to confront each of the Basran fifths and the pro-Zubayrid Kufans, while he remained stationary among his troops.
Mukhtar's forces made initial gains against the Basran Bakr and Abd al-Qays fifths and pressed forward.
They then drove back the Ahl al-Jibal fifth and approached Mus'ab who entrenched himself at an elevated position with his men and shot arrows against Mukhtar's troops.
Upon Mus'ab's urging, al-Muhallab, who had remained stationary with the Azd and Tamim fifths, led an assault against Mukhtar's troops and landed them a severe blow, though heavy fighting continued until nightfall.
[15][28] In the summation of historian Gerald R. Hawting, the "advantage gained" by the Zubayrids at Madhar "was pressed home and al-Mukhtar's forces were subsequently virtually destroyed at Harura".
[31] They returned and the siege was tightened until Mukhtar exited with some nineteen of his men and made a last stand, in which he was slain.
[33] Pressed by the vengeful Kufan ashrāf in his camp, including Muhammad ibn al-Ash'ath's son Abd al-Rahman, Mus'ab sanctioned wide-scale killings of Mukhtar's supporters in the city.
[33][34] According to the orientalist Henri Lammens, Mus'ab "executed a considerable number of his [Mukhtar's] supporters, which earned him as many enemies as his victims had relatives".
[30] According to an account by Abu Mikhnaf, Abd Allah ibn Umar ibn al-Khattab accused Mus'ab of massacring 7,000 Kufans,[32] while the account of al-Waqidi holds that of the partisans of Mukhtar in the palace who surrendered, Mus'ab executed 700 Arabs and all the Persians and afterward massacred 6,000 Kufan sympathizers.
[35] With the elimination of Mukhtar and the subsequent defection of Ibn al-Ashtar to the Zubayrids, Mus'ab gained full control of Iraq and assigned tax collectors to the Sawad and Jibal, both dependent districts of Kufa.