Uthman رضي الله عنه was succeeded by Ali ibn Abi Talib رضي الله عنه 656-611 the Prophet's صلى الله عليه و سلم cousin and a son-in-law (through the marriage of Fatima رضي الله عنها who died near the close of 632 or early 633), as the fourth and last of the Orthodox Caliphs. Abu Talib رضي الله عنه being poor, the Prophet صلى الله عليه و سلم took Ali رضي الله عنه into his care and brought him up in his household, as Abu Talib رضي الله عنه had done for him in his own childhood. Ali رضي الله عنه had become Muslim at the age of ten.He had also accompanied the Prophet صلى الله عليه و سلم in his migration in 622 from Makkah to Madinah, the Hijra.

In his youth, he had taken part in many famous battles such as Badr, Uhad and Khaybar, and had displayed exceptional bravery. The Prophet صلى الله عليه و سلم had more than once given him the standard to carry in battle. He had, however, remained in Madinah since the Prophet's صلى الله عليه و سلم death.

Soon after the murder of Uthman رضي الله عنه , a reaction set in, for even those who had previously been hostile to the Caliph were horrified by the incident. The people only now realised the gravity and likely repercussions of what had happened. Ali رضي الله عنه , on becoming Caliph, was strongly urged by leading Muslims, including the Companions Talha ibn Abdullah رضي الله عنه and Zubair ibn al-Awwam رضي الله عنه, to punish the murderers of Uthman رضي الله عنه .

For a time now, the authority of the state was completely undermined, and lawless elements roamed around unchecked. The assassination also once again opened up the old breach between the two rival clans, Umayya and Hashim; Uthmanرضي الله عنه had belonged to the former whereas Ali رضي الله عنه came from the latter. In the short period of the five years of Ali's رضي الله عنه Caliphate, there was nothing but internecine warfare and disaster.

Both Talhaرضي الله عنه and Zubair رضي الله عنه, who were distinguished Makkans, quarrelled with Ali and renounced their allegiance, which deprived Ali of considerable support at the start of his Caliphate. Talha had the honour of saving the Prophet's صلى الله عليه و سلم life in the battle of Uhad (625), while Zubair رضي الله عنه was renowned for his reckless gallantry in scaling the Roman fortress of Babylon during the conquest of Egypt and was also a son-in-law of the first Caliph, Abu Bark رضي الله عنه .

The Prophet's صلى الله عليه و سلم widow, Aisha رضي الله عنها , had gone to Makkah for the Pilgrimage, where Talha and Zubair رضي الله عنه joined forces with her and then proceeded to Basra, where the 'Battle of the Camel' (so-called because the fiercest fighting was round the camel on which Aisha رضي الله عنها was mounted) took place near the town in the month of December. The battle ended in a victory for Ali رضي الله عنه, but there were a large number of casualties. Talha رضي الله عنه and Zubair رضي الله عنه were both killed, but Aisha رضي الله عنها was treated with due respect and escorted back to Madinah where she retired from politics and lived for another twenty-two years before her death in 678. It was a new experience for the survivors to bury their dead, who had been killed in a battle not against the infidel, but of Muslims fighting against Muslims.

The aged Muslims viewed the whole situation with utmost sadness and mourned the loss of their companions from the earlier days, who had done so much for the spread of Islam while it was still in its infancy.