In September 1857 , the Baker-Fancher party , an emigrant group from Arkansas , camped at Mountain Meadows , a staging area in southern Utah used to prepare for the long crossing of the Mojave Desert by groups travelling westward to California . They were attacked by a combined group of Native Americans and Mormon militiamen dressed as Native Americans . There were multiple motives for the conflict , including a general atmosphere of rising tensions between the US Federal government and Mormon settlers ( see Utah War of 1857-1858 ) and a rumor that the Baker-Fancher party included those who had murdered Mormons at the 1838 event known as Haun 's Mill massacre
Haun 's Mill massacre
Haun's Mill massacre
John D. Lee