Cheyennes, Ogalallas, and Brule Sioux south of the Platte, together with probably a few Kiowas, Arapahoes, and perhaps some straggling Apaches and Comanches. It numbered from 800 to 1,000 lodges and from 2,000 to 3,000 warriors. The last-named bands are most likely on and south of the Arkansas River for the winter, but many come up to deprecate on the main and South Platte when grass comes. The party we met has no doubt gone north to the Powder River country, to join the hostile Indians there, and may be expected to continue their depredations along the North Platte till severely punished. Their probable route from where we left them will be through the sand hills to L'Eau-qui-court, then across the heads of White River and the South Fork of Cheyenne to Powder River. Small parties may remain, but the main body will go there to secure their families and recruit their stock until spring. They are well armed and mounted; have many rifled muskets and plenty of ammunition, including minie cartridges with ounce balls; are full of venom and bent on revenge for the loss of their people south. So soon as they reach the Indians north they will excite and perhaps compel them to become hostile. The posts on the Platte especially Deer Creek and Platte Bridge, which are within 100 miles of Powder River, will be in immediate danger. More troops should be sent out there immediately to hold the posts in the sub-district, and when spring opens important expeditions should be organized to penetrate the center of their country.

Having been nearly three years in this service and being about to leave it I venture to add a word as to the policy to be pursued. I beg to repeat the suggestions which I have heretofore made, that the permanent cure for the hostilities of the northern Indians is to go into the heart of their buffalo country and build and hold forts till the trouble is over. A hasty expedition however successful, is only a temporary lesson, whereas the presence of troops in force in the country where the Indians are compelled to live and subsist would soon oblige them to sue for peace and accept such terms as the Government may think proper to impose. The Black Hills, Big Horn Mountain, Yellowstone country, are all rich in minerals, but this wealth cannot be made available while hostile bands of Indians are roaming over the country. If these Indians could be induced to remove north toward the main Missouri and remain there, it would open up an immense region for mining and agriculture which cannot be now reached. They would be in a fine buffalo country, and out of the way of collisions with the whites, which are always liable to occur if they are near together. It would also separate them from the southern Indians, and prevent the plotting and combining which now exists between them. There are two points I would respectfully indicate as suitable locations for the posts spoken of one about the head of the Little Missouri of the Mandans near the Three Buttes, and the other at some proper place on Powder River. An expedition starting from the Missouri near Fort Pierre and following the old traders' trail west of the forks of the Cheyenne, thence to the head of the Little Missouri of the Mandans, thence to Powder River, would be joined at some proper post by another from Fort Laramie, and if in sufficient force it could hardly fail to accomplish its object.

I am, Captbedient servant,

WM. O. COLLINS,

Lieutenant Colonel Eleventh Ohio Vol. Cav., Commanding Western Sub-District.

Captain JOHN PRATT,

Assistant Adjutant-General, District of Nebraska.