After the battle at Sand Creek, the southwest tribes agreed to a series of treaties in 1865 by which new reserves were promised them on the borderland of Kansas and Indian Territory. These treaties were so amended by the Senate that for a time the tribes had no admitted homes or rights save the guaranteed hunting privileges on the plains south of the Platte. They seem generally to have been peaceful during 1866, in spite of the rather shabby treatment which the neglect of Congress procured for them. In 1867 uneasiness became apparent. Agent E. W. Wynkoop, of Sand Creek fame, was now in charge of the Arapaho, Cheyenne, and Apache tribes in the vicinity of Fort Larned, on the Santa Fé trail in Kansas. In 1866 they had "complained of the government not having fulfilled its promises to them, and of numerous impositions practised upon them by the whites." Some of their younger braves had gone on the war-path. But Wynkoop claimed to have quieted them, and by March, 1867, thought that they were "well satisfied and quiet, and anxious to retain the peaceful relations now existing."
The military authorities at Fort Dodge, farther up the Arkansas and near the old Santa Fé crossing, were less certain than Wynkoop that the Indians meant well. Little Raven, of the Arapaho, and Satanta, "principal chief" of the Kiowa, were reported as sending in insulting messages to the troops, ordering them to cut no more wood, to leave the country, to keep wagons off the Santa Fé trail. Occasional thefts of stock and forays were reported along the trail. Custer thought that there was "positive evidence from the agents themselves" that the Indians were guilty, the trouble only being that Wynkoop charged the guilt on the Kiowa and Comanche, while J. H. Leavenworth, agent for these tribes, asserted their innocence and accused the wards of Wynkoop.
The Department of the Missouri, in which these tribes resided, was under the command of Major-general Winfield Scott Hancock in the spring of 1867. With a desire to promote the tranquillity of his command, Hancock prepared for an expedition on the plains as early as the roads would permit. He wrote of this intention to both of the agents, asking them to accompany him, "to show that the officers of the government are acting in harmony." His object was not necessarily war, but to impress upon the Indians his ability "to chastise any tribes who may molest people who are travelling across the plains." In each of the letters he listed the complaints against the respective tribes--failure to deliver murderers, outrages on the Smoky Hill route in 1866, alliances with the Sioux, hostile incursions into Texas, and the specially barbarous Box murder. In this last affair one James Box had been murdered by the Kiowas, and his wife and five daughters carried off. The youngest of these, a baby, died in a few days, the mother stated, and they "took her from me and threw her into a ravine." Ultimately the mother and three of the children were ransomed from the Kiowas after Mrs. Box and her eldest daughter, Margaret, had been passed around from chief to chief for more than two months. Custer wrote up this outrage with much exaggeration, but the facts were bad enough.