The Battle of Nahrawan () was fought between the army of Caliph Ali and the rebel group Kharijites in July 658 CE (Safar 38 AH). They used to be a group of pious allies of Ali during the First Muslim Civil War. They separated from him following the Battle of Siffin when Ali agreed to settle the dispute with Mu'awiya, governor of Syria, through negotiations, a move labeled by the group as "against the Qur'an". After failed attempts to regain their loyalty and because of their rebellious and murderous activities, Ali confronted the Kharijites near their headquarters by the Nahrawan Canal, near modern-day Baghdad. Of the 4,000 rebels, some 1,200 were won over with the promise of amnesty while the majority of the remaining 2,800 rebels were killed in the ensuing battle. Other sources put the casualties at 1500–1800. The battle resulted in a permanent split between the group and the rest of the Muslims, whom the Kharijites, due to their extremist nature ("ghuluww"; غلو in Arabic), branded as apostates. Although defeated, they continued to threaten and harass cities and towns for several years. Ali was assassinated by a Kharijite in January 661. Background The controversial policies of the third Caliph Uthman resulted in a rebellion that led to his assassination in 656. Ali ibn Abi Talib, the son-in-law and cousin of Muhammad, was subsequently elected caliph by the Medinese people and the Iraqi dissidents present in Medina. His election was challenged by some of Muhammad's companions, including Talha ibn Ubayd Allah and Zubayr ibn al-Awwam, and by Muhammad's widow A'isha. Mu'awiya, the governor of Syria and Uthman's relative, also denounced Ali's election and demanded retribution against Uthman's killers. Although Ali defeated the rebellion of Talha and Zubayr in the Battle of the Camel in 656, his war against Mu'awiya resulted in a stalemate at Siffin in 657 when Mu'awiya called for arbitration by the Qur'an to avoid defeat. Ali's forces stopped fighting, despite repeated warnings from Ali that the appeal to their holy book was a deception. Nevertheless, an arbitration committee was set up with representatives from Ali's and Mu'awiya's sides with a mandate to settle the dispute in the spirit of the Qur'an. As Ali marched back to Kufa, his capital, schisms surfaced in his army. A group of his soldiers criticized the arbitration and accused Ali of blasphemy for leaving the matter to the discretion of two