Ali was an early convert to Islam and confidant of the Prophet. A dispute over his rights to succeed Mohammed forced him into retirement. But when the third caliph - Othman - was murdered, Ali was invited by the Muslims of Mecca to accept the caliphate. He based his caliphate on ideals of social justice and equality. This led to a rebellion by the aristocracy of Mecca.

The governor of Damascus, Mo'awiya, a kinsman of Othman's family, led a second rebellion and defeated Ali. This led to a major split in Islam between the Sunnites and Shi'ites. The Shia's consider him and his descendants the only true heirs of the Prophet.

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