The latter may be somewhat underestimated, but they do not in any case exceed in number 1,000 warriors. To these may be added about 400 Missouri Yanktons, with whom the Eastern Yanktonnais are intimately connected, and by whom they could ready be re-enforced.

You have therefore, general, within your department limits or immediately adjacent:

Refugee Medawakanton and Wahpetons.......................... 250

Lower Sissetons............................................. 100

Upper Sissetons and Eastern Yanktonnais.....................1,450

Missouri Yanktons........................................... 400

------

2,200

Making an aggregate force of 2,200 Sioux warriors, provided they are not strengthened by the Teton bands across the Missouri. The fractional brigade under my command, if aided by a few hundred mounted men to overtake and bring to bay these prairie savages, is able to whip the whole to them even if combined; but as they are well provided for the most part with good horses, they could easily elude the pursuit of footmen alone.

I think it may be safety calculated that one-half of the first 350 above set down will be captured and destroyed before spring, as they must come in from the prairie before winter.

I have made the foregoing enumeration, general, to furnish you with such information as may be useful to you in forming your plans for the future.

With regard to the proposed expedition against the Yanktons, rather Eastern yanktonnais, while I shall follow your orders in dispatching the force of mounted men when they arrive with the rest of the 650 led horses, I am frank to say that unless provided with abundant forage the horses will fail in less than ten days. The prairie grass is now dry and worthless, and not to be depended upon for campaign purposes at this late season of the year.

6 p.m.-Since writing the foregoing Adjutant-Blakely has arrived with his detachment, with 50 men and 100 horses, but without forage. We have nearly exhausted all the corn to be found within 20 miles, and the mounted men can effect but little without it.

I am, general, very respectfully, your obedient servant,

H. H. SIBLEY,

Brigadier-General, Commanding.

WAR DEPARTMENT,

Washington, October 18, 1862.

Major-General CURTIS, Saint Louis, Mo.:

I advised against the weakening of your forces at Helena. It is too important a place to risk. You are authorized to call upon the Governor of Illinois for such troops as he may have disposable.

H. W. HALLECK,

General-in-Chief.

DEPARTMENT OF MISSOURI, October 18, 1862.

Rear-Admiral DAVID D. PORTER, Commanding Illinois:

My force at Helena apprehends an attack. If you can add strength by sending more gunboats or making an effort, even as a feint to go