Ali ibn Abi Talib was one of the earliest converts to Islam and a close companion of the Prophet Muhammad.
After the assassination of Uthman, Ali was elected as the fourth Caliph, but his legitimacy was challenged by factions demanding retribution for Uthman's death.
He faced rebellion from Aisha, Talha, and Zubayr at the Battle of the Camel, and later from Muawiyah I at the Battle of Siffin.
Ali moved the capital to Kufa in Iraq. His leadership was defined by his commitment to justice and his struggle to maintain unity in a rapidly fragmenting empire.
He was assassinated by a Kharijite in 661, ending the Rashidun era and paving the way for the Umayyad Caliphate.