Members of Parowan's militia participate in killing 120 men, women, and children in Mountain Meadows Massacre. This is largest massacre of wagon train in American history and is unparalleled because killing begins as "whites" are escorting emigrants under flag of truce. After holding prayer circle, local LDS leaders decide not to await word from Brigham Young about whether to help Indians destroy emigrants. At pre-arranged signal, most Mormon participants dutifully kill unarmed emigrant waìking beside each militiamen, while some Mormons fire their weapons in air, and a few kill as many emigrants as they can. They spare eighteen small children. Apostle Amasa M. Lyman crosses the Meadows on route to Salt Lake City from California and meets militia as it returns from burying murdered emigrants. "The twilight had commenced and he knew many of them, but none of them spoke to him or his company." His son says, "The stench was nearly unbearable, and the cattle were nearly crazy smelling blood. . . . it was the most hideous sight he has spent." Decades later participants acknowledge various motivations for destroying this Missouri and Arkansas group which antagonized both Mormons and Indians of southern Utah: war hysteria that belligerent emigrants might incite California to send military force to combine with "invasion" from east by U.S. army; fear that Indians would attack isolated settlements if they didn't assist; "avenging the blood" of Missouri expulsion of 1838 and of Apostie Pratt's recent murder; desire to pìunder wagon train's property, which included 1,000 head of cattle, according to Church Historian's Ofïice on 28 Sept.. 1857; and intimidation by some Mormon firebrands who threatened to "blood atone" LDS militiamen who didn't want to participate. Brigham Young gives unsuccessful order to prevent massacre but becomes accessory after fact. He later tells participants that he approves of the massacre and lets them know he expects them to exonerate each other in court of law. He publicly intimidates anyone who is inclined to give evidence against Mormon participants. He refuses to give federal authorities information that would implicate nearly all adults of small Mormon community in massacre and division of victims' property. Then when total denial becomes impossible, Young scapegoats three men through excommunication and arranges for participants to testify (and jurymen to convict) only John D. Lee, Brigham Young's adopted son and Council of Fifty member.
[Source: The Mormon Hierarchy - Extensions of Power by D. Michael Quinn, [New Mormon History database ( http://bit.ly/NMHdatabase )]]