Snelling last night, and will reach the immediate vicinity of that post to-day, and will go into camp until further orders. It consists of the Sixth and Seventh Regiments of Minnesota Volunteers, and one section each of 6-pounders and mountain howitzers.

I would respectfully suggest for the consideration of Major-General Pope, that at least one-third instead of one-fourth of the officers and men who have participated in the long and tiresome campaign just closed be permitted to visit their homes at the same time, so that opportunity be given to all of them to do so before marching orders. In fact, if one-half were granted immediate leave of absence for a limited period, the whole matter would be much simplified, especially as the residence of many of the officers and men is remote from this pint.

I have carefully perused General Pope's dispatch of 29th ultimo, relative to the disposition of the forces to remain in the State during the approaching winter.

I would respectfully recommend that at least two regiments of infantry in addition to the mounted men of Hatch's battalion and those contemplated to be re-enlisted from the Mounted Rangers be retained for the protection of the border.

The Upper Sioux are desirous to have re-established their former amicable relations with the Government, and I think may be made to deliver up, as the price of peace, those of the lower bands who were actors in the tragedies of 1862. But they are in constant intercourse with the Red River half-breeds, and would promptly be informed of the reduction of the force in this district through them, and, if impressed with an idea that the diminution was so great as to prevent the Government from further chastising them in case it became necessary, they might be emboldened to continue the war, and thereby necessitate another expedition for their complete subjugation.

As a measure of economy, therefore, I do not think it would be prudent at the present crisis to weaken too much the military force in this district.

So soon as the requisite information can be obtained, I will dispatch to you a full statement of the arrangements proposed to be made for the defense of the frontier, for the consideration of the major-general commanding.

I beg leave to state that Fort Abercrombie is already inclosed with a stockade sufficient for defensive purposes, and that earthworks have been erected at Fort Ridgely for the security of that post. The defenses at Fort Ripley are also in good condition, a stockade having been built on all sides, excepting on the river front, where Colonel Thomas does not deem one necessary.

I would respectfully request that none of the regiments to be ordered south receive marching orders before the 15th October, by which time all will have had opportunity to visit their homes, and the season for apprehending Indian raids will have passed. As instructed by General Pope, I will indicate in a very few days the regiment or regiments to be posted in this State.

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

H. H. SIBLEY,

Brigadier-General, Commanding.

J. F. MELINE,

Acting Assistant Adjutant-General.