As the Indians were entirely dependent upon the buffalo for subsistence, the buffalo became the controlling factor in the change that then took place, by refusing to no longer cross the road, and the buffalo took up their permanent abode north of the Platte River, the last of the buffalo passing in 1874. There were different ideas as to what impelled the buffalo to come to this conclusion, but most probably the smoke and noise, and the terrible appearance of the engine, resembling huge monster animals, prevented the buffalo from attempting to cross, and consequently they never returned south after their northern trip in '74. The Indians, of course, for obvious reasons, following permanently. There can be no reasonable doubt but that the forebears of these Indians and these buffalo were the companions of Coronado in his wonderful exploration (for that day), from the Pecos to the Platte (over four hundred years ago) at the great forks near the present city of North Platte and these Indians were the adversaries we were to meet at Rosebud. Here at North Platte, while the buffalo were hesitating to go north permanently, I often met and became well acquainted with Spotted Tail, Chief of the Brulés, the greatest and best chief I ever knew. Spotted Tail, with a great portion of his Ogallalas, remained around North Platte until some time in 1873, when his agency was established on the headwaters of the White River, on a branch called Bear Creek, near the boundary between Nebraska and Dakota. Here he assembled all his tribe, some four thousand. In the winter of 1874-5 General Crook directed me to follow Spotted Tail and build at his agency a five-company post, to be called Camp Sheridan (three cavalry and two infantry companies), in which Lieutenant Lemly assisted. Like Carrington, we were furnished with everything necessary: soldier labor, saw, shingle and lath mills, hardware and some thirty skilled artisans, and as we were in a pine forest, many trees were felled, and the lumber from them placed in the building on the same day. There were no contracts, no delays in construction, and it was probably the cheapest, most satisfactory, and most rapidly constructed post ever built by the Army. Shortly after this Lieutenant Colonel Custer, with an expedition including engineers, mining experts, and geologists, had been ordered to make an exploration of the Black Hills. Custer returned, reporting gold in the hills, which excited the western people so they began to move in from all directions. This again aroused the Indians, and it became apparent that there would be trouble. General Sheridan issued orders to myself and adjacent commanders to prevent the whites from violating the Indian non-intercourse law by arresting and destroying outfits for that purpose.