About: The association of millennialist movements with violence has been a subject of much study following recent high-profile events. This article examines a case of millennialism and violence that occurred just over 150 years ago. It tracks the events leading to the attempted assassination of Nasir al-Din Shah of Iran in 1852 by a small group of followers of the religion of the Bab, a religious leader who claimed to fulfill the prophecies of Shi'i Islam about the coming of the Imam Mahdi. The factors leading to the violence are analyzed and compared with other cases of millennialism and violence. The main factors that stand out in this case include: a pre-existing religious milieu that expected a violent, millennial event and engendered a radically dualist worldview, with the shah's government as the embodiment of an evil destined to be defeated and removed; a severe persecution of the group resulting in some followers' desire for revenge and a dramatic violent act that would bring divine intervention and ultimate victory; government removal of moderate leadership, leaving only radical extremist leaders; and the presence among the Tehran group of Babis, which carried out the attempted assassination, of a charismatic leader whom these Babis believed had access to a source of divine power that could make the plan achievable, when a more rational analysis would have demonstrated the opposite.