In the late summer of 1854, about 4,000 Brulé and Oglala were camped near Fort Laramie in accordance with the terms of the Treaty of 1851. On August 17, a cow belonging to a Mormon travelling on the nearby Oregon Trail was killed by a Minneconjou named High Forehead. Lt. Hugh Fleming, the senior officer at the fort, called on Conquering Bear, so that the matter could be discussed. Lt. Fleming was evidently unaware, or chose to ignore that matters of that nature were, by the terms of the Treaty of 1851, to be handled by the local Indian Agent, in this case John Whitfield, who was due to arrive within days. Conquering Bear, however, was fully aware that the matter should not concern the military, but he still attempted to negotiate, and did not consider the matter serious. Conquering Bear offered the cow’s owner his choice of any of his 60 horse herd. The owner refused, demanding $25 instead. Lt. Fleming demanded that the Sioux arrest High Forehead and deliver him to the fort, to which Conquering Bear refused. That day’s negotiations ended with no result.
The next day, Second Lieutenant John Lawrence Grattan, of the U.S. 6th Infantry Regiment, a recent graduate of West Point, was allowed to lead a detachment into the Indian encampment to bring in the guilty Lakota cow-killer. Grattan was an inexperienced, short-tempered young man, openly contemptuous of the Lakotas’ ability as warriors and who was looking to prove himself. This would be his first interaction with the Sioux. A commander at Laramie later recalled, “There is no doubt that Lt. Grattan left this post with a desire to have a fight with the Indians, and that he had determined to take the man at all hazards.” Grattan took with him a sergeant, a corporal, 27 privates and a French-American interpreter named Luciene Auguste, along with two artillery pieces.