The second half of Uthman's reign was dogged by a charge that has followed him ever since: that he favoured his own Umayyad relatives, appointing them to the richest governorships, Muawiya in Syria, and his foster-brother and kinsmen in Egypt and Iraq, and that he let his cousin Marwan dominate his administration. Discontent gathered in the garrison towns of Kufa, Basra and, above all, Egypt, whose grievances were as much about the division of conquest revenue as about piety.
In 656 armed provincials came to Medina, blockaded the caliph in his house, and after a standoff broke in and killed him. He is said to have refused to let his supporters shed Muslim blood in his defence, and to have been struck down with a copy of the Quran open before him, an image the tradition has never forgotten. He was the first caliph to be murdered, and by a Muslim mob rather than an external enemy.
His death did not settle anything; it opened the first fitna. Ali, chosen as the next caliph, was at once challenged by those who demanded vengeance for Uthman: first Aisha, Talha and Zubayr at the Battle of the Camel, then Muawiya, who raised Uthman's bloodied shirt as a banner at Siffin. The civil wars that followed hardened into the enduring division between what became Sunni and Shia Islam, which is why Uthman's assassination is reckoned one of the hinge events of Islamic history.