First Fitna

The First Fitna (Arabic: الفتنة الكبرى) was the first civil war in the Islamic community. It led to the end of the Rashidun Caliphate and the establishment of the Umayyad Caliphate. The civil war involved three main factions: the supporters of Ali, the fourth Rashidun caliph; the Uthmaniyya (partisans of the slain caliph Uthman, comprising Aisha's faction in Basra and Mu'awiya's Umayyad partisans in Syria); and, from 657 onward, the Kharijites, who seceded from Ali's camp following the arbitration at Siffin.

The roots of the first civil war can be traced back to the assassination of the second Rashidun caliph, Umar. Before he died from his wounds, Umar formed a six-member council which elected Uthman as the next caliph. During the final years of Uthman's caliphate, he was accused of nepotism and killed by rebels in 656. After Uthman's assassination, Ali was elected the fourth caliph, though his accession was immediately clouded by the unresolved murder of his predecessor. Aisha, Talha, and Zubayr represented the initial opposition to Ali's rule. They argued that Ali had failed to prioritize the prosecution of Uthman's killers and revolted to demand a new elective council. The two parties fought the Battle of the Camel in December 656, from which Ali emerged victorious. Afterwards, Mu'awiya, the long-time governor of Syria and a kinsman of Uthman, also refused to recognize Ali as caliph. He declared war on the basis of his right to seek blood-revenge for his cousin. The two parties fought the Battle of Siffin in July 657, which ended in a stalemate and arbitration.

This arbitration was resented by the Kharijites, who declared Ali, Mu'awiya, and their followers to be infidels. Following Kharijite violence against civilians, Ali's forces crushed them in the Battle of Nahrawan. Soon after, Mu'awiya also seized control of Egypt with the aid of Amr ibn al-As.

In 661, Ali was assassinated by the Kharijite Abd al-Rahman ibn Muljam. After Ali's death, his eldest son Hasan was acclaimed as his successor in Kufa. Mu'awiya quickly marched on Kufa with a large army. The embattled Hasan concluded a peace treaty, acknowledging the rule of Mu'awiya, who subsequently founded the Umayyad Caliphate and ruled as its first caliph.