“On August 18  a lame cow wandered away from Mormon emigrants hurrying westward. When the stray cow reached the Sioux encampment it was quickly butchered. From this trivial occurrence ensued a tragic series of errors for which fort [Laramie] commander Hugh B. Fleming and Lieutenant John L. Grattan bore almost complete responsibility.
Although the Sioux chief offered generous payment—a horse—for the emigrant animal, somehow the circumstances were utilized to force a major confrontation the next day. Grattan, a firm believer in severely punishing Indians for all their mistakes, demanded the arrest of the offending Miniconjou Sioux brave—who was a guest at the Brulé village. Grattan ineptly attempted a show of force with his contingent of twenty-eight men, refusing a mule as compensation for the now-important cow. A few shots were fired and an Indian was wounded, but the chiefs cautioned their wariors not to return the fire, hoping the whites had now had their vengeance.
But Grattan was not to be denied, and he ordered another volley in which the Sioux chief was killed. Reprisal came swiftly. All twenty-one soldiers and their interpreter were killed; their bodies, especially Grattan’s were badly mutilated. The enraged Sioux raided trading posts around the fort and that fall made a series of attacks on mail carriers, killing at least three.”