His mother, Sarah Rogers, died when he was only five and his father, Peter Grattan, relocated with his young son, John, and daughter, Mary, to Lisbon, New Hampshire where he worked as a wheelwright.

Given the customary three months leave following his graduation, Grattan was to have reported to Company G, 6th Infantry, at Fort Laramie, by October 1, 1853, but he arrived on November 16.

Within his first month, according to recorded reports from Post Surgeon Charles Page, Grattan received a reputation as being brash and boastful, while also giving off the impression that he was proud to serve in the army.

The most disturbing trait, according to later accounts given by Page, was that Grattan displayed a disdain and dislike of the American Indians, despite having had no contact with them whatsoever up to that point, save seeing or meeting any who were in or around the post.

In reality, the settlers and traders who were pursuing the band of warriors had enough experience to recognize that the Cheyenne seemed to be baiting them into a possible ambush, thus they stopped their pursuit and reported the incident to Fort Laramie.

In the Native American camps, seasoned chiefs were struggling to control the more impatient young warriors, who were angered by the sight of their people starving, and over former broken promises by the whites.

Reports vary, with the most reliable accounts stating that the owner noticed that the cow was missing, and returned to find that the Indians had butchered it.

In reality, a matter of this sort should have been handled by John Whitfield, the Indian Agent assigned to the area, who was due to arrive within the week.

However, as negotiations went on, it was quickly evident that Lt. Fleming's inexperience led to him being easily swayed and influenced, in this case by the civilians involved.

Finding himself encouraged by Lt. Grattan's support, the formerly uncertain Lt. Fleming now demanded that High Forehead be arrested and brought to the fort.

Another poor decision on the part of Fleming, as the entire post was made up of only 75 soldiers, and that day 32 were away on wood and hay cutting details.

Sergeant Leodegar Schnyder, would later say he did not volunteer due to his belief that the two inexperienced officers were making bad decisions, and thus, not being ordered to go, he did not.

Lt. Grattan, having no prior experience with the Indians whatsoever, was now leading his small force into a major Sioux encampment which was filled with young warriors tired of what they considered to be lies told by the white government.

Halfway into the village, now seeing painted warriors who were openly hostile and riding aggressively around the column, Lt. Grattan stopped, and asked the advice of James Bordeau, an experienced trader who had lived on the frontier for many years.

Bordeau had been at Fort Laramie when the earlier incident happened with Conquering Bear, and was in the village trading when the army column entered.

At this point Auguste was calling the Sioux warriors women, and was riding wildly around on his horse saying they had come to fight, not to talk.

However, when he reached about twenty five yards distance from the meeting spot, he observed the flanking movements of the Indians, and could hear the heated exchange between Lt. Grattan and Conquering Bear, he again retreated.