The Mountain Meadows Massacre was a series of attacks during the Utah War that resulted in the mass murder of at least 120 members of the Baker–Fancher emigrant wagon train. The massacre occurred in the southern Utah Territory at Mountain Meadows, and was perpetrated by settlers from the Church of Jesus Christ of Latter-day Saints involved with the Utah Territorial Militia who recruited and were aided by some Southern Paiute Native Americans. The wagon train, made up mostly of families from Arkansas, was bound for California, traveling on the Old Spanish Trail that passed through the Territory.

The Utah War (1857–1858), also known as the Utah Expedition, the Utah Campaign, Buchanan's Blunder, the Mormon War, or the Mormon Rebellion, was an armed confrontation between Mormon settlers in the Utah Territory and the armed forces of the US government. The confrontation lasted from May 1857 to July 1858. The conflict primarily involved Mormon settlers and federal troops, escalating from tensions over governance and autonomy within the territory. There were several casualties, predominantly non-Mormon civilians. Although the war featured no significant military battles, it included the tragic Mountain Meadows Massacre, where Mormon militia members killed about 120 unarmed settlers traveling to California.