Mormons and Paiutes murder 120 emigrants at Mountain Meadows

On September 11, 1857, the Mountain Meadows Massacre took place. Mormons dressed as Indians and Paiute Indians murdered 120 colonists in Utah. From the article:

"Mormons and Paiutes murder 120 emigrants at Mountain Meadows
Mormon guerillas, stoked by religious zeal and a deep resentment of decades of public abuse and federal interference, murder 120 emigrants at Mountain Meadows, Utah on September 11, 1857.

Although historical accounts differ, the conflict with the wagon train of emigrants from Missouri and Arkansas apparently began when the Mormons refused to sell the train any supplies. Some of the emigrants then began to commit minor depredations against Mormon fields, abuse the local Paiute Indians, and taunt the Mormons with reminders of how the Missourians had attacked and chased them out of that state during the 1830s. Angered by the emigrants’ abuse and fired by a zealous passion against the growing tide of invading gentiles, a group of Mormons guerillas from around Cedar City decided to take revenge. Cooperating with a group of Paiute Indians who had already attacked the train on their own initiative, the Mormon guerillas initially pretended to be protectors. The guerillas persuaded the emigrants that they had convinced the Paitues to let them go if they would surrender their arms and allow the Mormons to escort the wagon train through the territory. But as the train again moved forward under the Mormon escort, a guerilla leader gave a pre-arranged signal. The Mormons opened fire on the unarmed male emigrants, while the Paiutes reportedly murdered the women. Later accounts suggested that some Mormons had only fired in the air while others killed as few of the emigrants as they could. But when the shooting stopped in Mountain Meadows, 120 men and women were dead. Only 18 small children were spared.

As a direct result of the Mountain Meadows Massacre, the U.S. government demanded a new settlement from Brigham Young. In 1858, the Mormons agreed to accept a continued presence of federal troops and a Gentile governor for Utah Territory. No further significant Mormon-Gentile violence occurred, and the Latter Day Saints were thereafter largely left to govern themselves. But the era of complete Mormon domination of Utah ended as a result of the tragedy that day in Mountain Meadows."