On August 19, 1854, U.S. Army lieutenant John L. Grattan led a detachment of twenty-nine soldiers and one civilian interpreter to a large Lakota encampment near Fort Laramie to arrest an Indian man accused of killing a Mormon emigrant’s cow. The terrible series of events that followed, which became known as the Grattan Massacre, unleashed the opening volley in the First Sioux War—and marked the beginning of a generation of Indian warfare on the Great Plains. All Because of a Mormon Cow tells, for the first time, the full story of this seminal event in the history of the American West.  All Because of a Mormon Cow offers a better understanding even as it evokes the drama of a highly controversial episode in the history of relations between Indians and non-Indians in the American West.