In 656, finally a group of Muslims disaffected by Uthman’s rule conspired against the caliph and murdered him. By communal consensus, Ali succeeded Abu Bakr and became the Fourth Rightly Guided Caliph (Khulafa al-Rashidun). Two Muslim generals, Talhah and Zubayr, in collaboration with the Prophet’s youngest wife Ayeshah, revolted against Ali and accused him of having had a hand in the murder of Uthman. Ali defeated them in the Battle of Camel (so-called because Ayeshah participated in this battle, mounting a camel) near Basra in 656. A year later, in May-July 657, Ali faced yet another rebellious army, this one led by Mu’awiyah, again using the murder of Uthman as a pretext and challenging Ali’s authority. Ali faced Mu’awiyah’s army in the Battle of Siffin on the banks of the euphrates. Ali was about to win this battle too when Mu’awiyah ordered pages of the Qur’an raised on lances, thereby asking for arbitration. Ali agreed, but a band of his followers became so angry at this decision that they parted ways [kharaja] with him and formed the radical sect of the Kharijites. one of these angry Kharijites, a man named Abd al-Rahman ibn Muljam, fially killed Ali on 27 January 661. Ali’s son Hasan was in no mood to engage Mu’awiyah in any battle, and thus Mu’awiyah proceeded to establish the Umayyad dynasty, which lasted until the advent of the Abbasid revolution in 750. The battles of Camel and Siffin anticipated the Battle of Karbala and wrote the blueprint for the rest of Shi’i history.Hamid Dabashi (2011). Shi’ism: A Religion of Protest, p. 108-09.
The first war in the caliphate of ‘Ali, which is called the Battle of the Camel, was caused by the unfortunate class differences created during the period of rule of the second Caliph as a result of the new socioeconomic forces which caused an uneven distribution of the public treasury among members of the community. When chosen to the caliphate, ‘Ali divided the treasury evenly as had been the method of the Holy Prophet, but this manner of dividing the wealth upset Talhah and Zubayr greatly. They began to show signs of disobedience and left Medina for Mecca with the alleged aim of making the pilgrimage. They persuaded “the mother of the Faithful” (umm al-mu’minin), A’ishah, who was not friendly with ‘Ali, to join them and in the name of wanting to revenge the death of the third Caliph they began the bloody Battle of the Camel. This was done despite the fact that this same Talhah and Zubayr were in Medina when the third Caliph was besieged and killed but did nothing to defend him. Furthermore, after his death they were the first to pay allegiance to ‘Ali on behalf of the immigrants (muhajirun) as well as on their own. Also, the “mother of the Faithful,” A’ishah, did not show any opposition to those who had killed the third Caliph at the moment when she received the news of his death. It must be remembered that the main instigators of the disturbances that led to the death of the third Caliph were those companions who wrote letters from Medina to people near and far inviting them to rebel against the Caliph, a fact which is repeated in many early Muslim histories.Seyyed Hossein Nasr (1989). Expectation of the Millenium: Shiism in History, p. 143
[F]or 25 years people had been encouraged to oppose Ali. It was therefore difficult for them to accept his vicegerency and caliphate or to acknowledge his exalted rank. … [I]t was not possible for worldly men to accept Ali’s justice, particularly since their self-indulgence had been given a free rein during the caliphate of Uthman. Hence, they rose against him, so that somebody who could satisfy their desires might assume power. Their wishes were fulfilled during the caliphate of Mu’awiya. Accordingly, Talha and Zubair at first swore allegiance to Ali, but when their demands for authority were not satisfied, they broke their allegiance and openly opposed him in the Battle of the Camel. [H]istory tells us who the real instigator was of the disturbances from the beginning of the caliphate. Was it any other than Ummu’l-Mu’minin A’yesha? Was it not A’yesha who, according to the statements of both Sunni and Shia traditionists, mounted on a camel (against the express ordinance of Allah and His Holy Prophet that she should stay in her house) reached Basra and provoked a large battle? You claim that internecine battles were due to Ali’s lack of political insight. This is a highly misleading statement. If A’yesha had not revolted against him, no one would have had the courage to oppose Ali, after the Holy Prophet had clearly declared: “To fight against Ali is to fight against me.” A’yesha incited the people to fight against Ali.Sultanu’l-Wa’izin Shirazi (1996). Peshawar Nights, p. 414.
When the second imam (al-Hasan) died, his brother and heir to the imamate, al-Husayn, assumed the burial responsibilities. In a story recounted in each of the main biographies, al-Husayn’s attempt to fulfill the dying wish of his brother was thwarted by ʿAʾisha, the daughter of Abu Bakr and the beloved and infamously young wife of the Prophet. Al-Hasan had desired to be buried next to his grandfather, the Prophet Muhammad, but the burial site was part of the property on which ʿAʾisha still lived. As al- Husayn approached with the funeral party, ʿAʾisha mounted a mule and bodily prevented the attempt to use that space for al- Hasan’s burial. A verbal altercation between al- Husayn and ʿAʾisha ensued. Eventually, due to al- Hasan’s other dying request that blood not be shed, al- Husayn led the party to the burial site of Fatima al- Zahraʾ, their mother. There he buried his brother’s body. … [A’isha’s role] set up the most memorable line of this story— found in every account— when Ibn ʿAbbas criticizes ʿAʾisha by saying, “What mischief you bring about, one day on a mule and one day on a camel!” This allusion to ʿAʾisha’s role in the Battle of the Camel (named for the steed on which she sat and watched) is both humorous and tragic, and it serves to remind the audience that ʿAʾisha had already betrayed one imam when she led the community of believers into civil war against ʿAli.Matthew Pierce (2016). Twelve Infallible Men: The Imams and the Making of Shi’ism, p. 80