SIFFIN, BATTLE OF

(MayJuly 657), series of negotiations and skirmishes during the first Muslim civil war (fitnah; 656661), ending in the arbitration of Adhruh (February 658January 659), which undermined the authority of 'Ali as fourth caliph and prepared for establishment of the Umayyad dynasty. Mu'awiyah, governor of Syria, refused to recognize 'Ali as the new caliph, calling instead for vengeance for the blood of his murdered kinsman, the third caliph, 'Uthman. 'Ali responded by invading Syria. The two armies met along the Euphrates River at Siffin (near the Syrian-Iraqi border), where they engaged in an indecisive succession of skirmishes, truces, and battles, culminating in the legendary appearance of Mu'awiyah's troops with copies of the Qur'an impaled on their lancessupposedly a sign to let God's word decide the conflict. 'Ali delegated Abu Musa al-Ash'ari as his representative, while Mu'awiyah sent 'Amr ibn al-'As. The two men, on the basis of the Qur'an and the traditions (Hadith) of the Prophet and in the presence of witnesses, were to decide whether 'Uthman had been guilty of abusing the divine law. If he had sinned and his murder was justified, then 'Ali's position as caliph would be secure; a verdict of innocence, however, would justify Mu'awiyah's attempts at vengeance and dislodge 'Ali. In a meeting at Adhruh (in present Jordan; some suggest Dumat al-Jandal, in present Saudi Arabia) in February 658, the arbitrators decided on 'Uthman's innocence. 'Ali immediately denounced the decision as invalid and reneged on his oath to be bound by the arbitration; Mu'awiyah, meanwhile, was proclaimed caliph by some of his Syrian supporters. In January 659 the arbitrators met at Adhruh, formally deposed both 'Ali and Mu'awiyah, then discussed the candidacy of 'Abd Allah ibn 'Umar and Mu'awiyah for the caliphate; no decision was reached. 'Ali and Mu'awiyah retained their own partisans, but, as Mu'awiyah's authority began to expand into Iraq and the Hejaz (western Saudi Arabia), 'Ali's diminished to Kufah, his capital. With 'Ali's assassination in 661, Mu'awiyah was free to establish himself as the first caliph of the Umayyad house.