The assassination of the Caliph Uthman sent shockwaves throughout the Muslim world. The murderers fled, and rumours spread about who was involved. Talha and Zubayr left Medina and went to Makkah, where they joined Aisha in calling for the punishment of Uthman's murderers. Ali, who was a close relative of the Prophet and married to his daughter Fatima, was proclaimed the new Caliph in Medina. Although Ali held a position of utmost veneration, his six-year caliphate was filled with quelling internal rebellions.
Ali was a famous warrior. He was given the honorific title, Lion of God (Asad-ullah).
Ali was brought up in the household of the Prophet and married to his daughter Fatima. His sons Hasan and Husayn were the sole heirs for the transmission of the Prophet's bloodline to future generations, and in time came to be considered, along with Ali, the first three Imams in Shi'ite doc trine. Even with the Sunni majority, Ali held a position of utmost veneration. He was extremely pious, ascetic, handsome, and a famed warrior. His eloquence, knowledge, and wisdom were legendary. The Prophet had famously said that Ali was to him "as Aaron was to Moses"; declared him to be the wisest of the Companions in judgment; and kept him close by his side throughout his life.
During the Battle of Khaybar, the Muslim forces were struggling for several days to breach the defences of the fortress. The Prophet Muhammad ﷺ said "I will certainly give the flag (standard) tomorrow to a man through whom Allah will grant us victory. He loves Allah and His Messenger, and Allah and His Messenger love him." All the Companions hoped it would be them. The next morning, the Prophet gave the flag to Ali, saying, "O Allah, grant him strength and support him with the Holy Spirit." Ali led the Muslim forces to victory the same day displaying great courage and unstinting patience against the enemy.
After Uthman's murder, Aisha called for Ali to have the traitors punished for their crime. Ali said he could not punish the murderers of Uthman as their identities were not known to him. An army came forth from Makkah, led by Aisha, Zubayr, and Talha, to demand justice for Uthman. They faced Ali's forces near Basra. The Companions did not want to fight each other, but some malicious elements in the armies triggered hostilities. Aisha rode into the battle in a tent on the back of a camel, but Ali's side was victorious. Zubayr and Talha were killed, and Ali forbade any taking of prisoners or booty as the vanquished were fellow Muslims. Aisha was received with full honour and given an escort to Medina under the guard of her brother, Muhammad, and the Prophet's grandson, Hasan. After this, Ali moved his capital from Medina to Kufa in Iraq to avoid bloodshed on the sacred soil of the Prophet's city.
After the 'Battle of the Camel', as it became known, Ali faced a rebel army from Syria led by Muawiya son of Abu Sufyan. It was to Muawiya that Marwan had fled. The Syrians also refused to accept Ali as caliph. During the conflict with Muawiya, a faction separated from Ali's army, and encamped at a place called Harura. This fation declared that both Ali and Muawiya, and all those with them, had apostatized from Islam (become unbelievers).
The Prophet ﷺ had warned the Companions to look out for this sect, and there are many hadiths about their vile nature. The Prophet ﷺ said that they appear outwardly to be very religious, but inwardly they lack faith. Ali recognised them from the descriptions that he had heard from the Prophet ﷺ, and he fought them valiantly until they were almost all vanquished. Later, the scholars named this troublesome sect, the Kharijites (Khawarij). One of the negative characteristics of this sect is that they consider themselves superior, and accuse all other Muslims of being unbelievers, and then proceed to declare war against them, and cause bloodshed and unrest.
Although Ali's six-year caliphate was filled with quelling internal rebellions, he held a position of respect with all Muslims. His spiritual authority was only enhanced when he stood side by side with his sons, Hasan and Husayn, the sole inheritors of the prophetic bloodline.
Even Ali's enemies could not deny his high position, but the tragic murder of the Caliph Uthman was not easily forgiven or forgotten, and it led to the First Fitna or Civil War in Islam. There were many eye-witness reports, and often contradictory versions of events circulated.
Later generations of scholars and historians of Islam would have the painstaking job of trying to filter the facts and uncover what had really occurred. In the end, Ali was also murdered. A Kharijite assassin leapt out during the Fajr prayer and struck him down while he prayed (may God have mercy on him).
Once a Jewish man had a disagreement with Ali, who was Caliph at the time, about some item of property. The case was taken to the qadi (judge). The Qadi asked Ali if he had any witnesses to support his claim. Ali called forth his son, Hassan, as witness. The Qadi said that he cannot accept a son's witnessing in support of a father. "Even if he is the leader of the youths of Paradise?" asked Ali (this was the title the Prophet gave to his grandsons, Hasan and Husayn). 'Even so,' replied the Qadi, and ruled in favour of the Jew. The Jew, meanwhile, was so amazed at what had happened that he promptly embraced Islam!
Ali's favourite nickname was Abu Turab. It came about one day when the Prophet saw Ali getting up after sleeping on the ground, and he was covered in dust. "O Abu Turab!" the Prophet said. Ever since that day, he became known as Abu Turab...'Father of Dust'.