The Assassination of Joseph Smith, which also killed his brother Hyrum Smith, transformed a contest over the future of the Latter-day Saints into a succession crisis shaped by plural marriage, contested justice, and calls for revenge. The killing left the church without its central leader at a moment when its factions were already divided over whether his successor should preserve or repudiate the practice.

A leadership crisis already in motion

Before the assassination, committed opponents of polygamy—including Emma Smith, Samuel H. Smith, and Sidney Rigdon—wanted a successor who would revoke the doctrine. On the other side, John Taylor, Willard Richards, Brigham Young, and other apostles sought a leader who would uphold it, protecting the standing of plural wives and the future of the practice. The murder did not create this divide, but it made the question of succession urgent.

The crisis was complicated by the absence of much of the Quorum of the Twelve Apostles. Ten members, including Brigham Young, had been sent across the country to promote Joseph Smith’s presidential campaign. Young was in Massachusetts when the prophet was killed and did not learn of the death until nineteen days later. The news left him fearing that the church would disintegrate without Joseph Smith; he and the other apostles hurried back to Nauvoo.

Competing claims to Joseph Smith’s mantle

While the apostles were away, the anti-polygamy faction moved to install a successor before their return. Joseph Smith III had the strongest hereditary claim, but he was still a child, so his supporters turned to his uncle Samuel H. Smith. Samuel seemed close to securing the position, but he died abruptly. The account reports circumstantial evidence suggesting that Hosea Stout, chief of the Nauvoo police and an ally of Brigham Young’s faction, poisoned him; the allegation is presented as suspicion, not as an established finding.

Sidney Rigdon then made a last effort to claim Joseph Smith’s leadership. He secured an appointment as guardian of the church, subject to confirmation at a churchwide meeting scheduled for August 8. Brigham Young and the returning apostles reached Nauvoo on August 6, interrupting the effort to install Rigdon. The killing had thus opened a contest in which rival claims to authority were inseparable from the dispute over plural marriage.

The trial and its acquittals

In May 1845, nine men were indicted for the murders of Joseph and Hyrum Smith; seven were brought to trial in Carthage. The defendants included prominent local figures: officers of the Carthage Greys, an Illinois state senator, and the editor of the Warsaw newspaper. Anti-Mormon hostility in Hancock County made a conviction unlikely, while John Taylor and Willard Richards, who had witnessed the murders, refused to appear because they feared they would be killed if they went near Carthage.

The account records that the defendants were found not guilty on May 30. Latter-day Saints had expected the verdict, but it still provoked anger. With the prosecution unable to deliver a conviction, the killing was framed within the community not only as a crime but as a wrong that earthly courts had failed to redress.

Vengeance and the violence that followed

A month after the acquittals, on the first anniversary of Joseph Smith’s death, Brigham Young declared that God and his people were responsible for avenging the blood of the church’s leaders. He directed church authorities to institute a formal Oath of Vengeance as part of the temple endowment ceremony. Participants pledged to pray for vengeance and to teach that obligation to their descendants through the third and fourth generations. The oath remained in the ceremony until 1927, when its disclosure in the non-Mormon press prompted public and political condemnation.

Retaliation and expulsion also unfolded beyond the temple. After the assassination, anti-Mormon attacks on the Saints intensified. During the summer of 1845, vigilantes led by Levi Williams—the principal defendant in the murder trial—burned Mormon homes and farms across the county. By September 15, forty-four Mormon residences had been destroyed. The aftermath therefore extended well beyond the question of who would succeed Joseph Smith: the acquittals, the vow of vengeance, and the attacks on Nauvoo’s community deepened the conflict that would drive the Saints from Hancock County.