This officer (the commander of the force north of the Missouri) will also notify the commanding officer of the four companies of infantry encamped on the upper Cheyenne, by runners or otherwise, and by duplicate or triplicate letters sent on different days, to move forward to Devil's Lake and establish the post. In order to assure the receipt of this notification, he will also report the facts to General Sibley, who will thereupon also notify the infantry companies. As soon as military operations are over for the season, the commanding officer of the troops operating north of the Missouri River will detail the five cavalry companies to form the cavalry garrison of the post at Devil's Lake, nd will himself, with the five cavalry or mounted companies to constitute the mounted portion of the garrison of the post on James River, proceed to that post and assume command thereof. General Sibley will designate the permanent commander of the post at Devil's Lake. Brigadier-General Sibley will extend the jurisdiction of these officers over such districts of country as he may think judicious or convening.

Before the commander of the force operating north of the Missouri proceeds to join his post on james River he will give special instruction to the commanding officer of the five cavalry companies destined for Devil's Lake, so that the proper measures be taken to bring forward the winter supply for the garrison of that post from the post on the Missouri River near mouth of Long Lake. The public animals will be sent, before the winter sets in, from Devil's Lake to the post on the Missouri to be wintered. The public animals belonging to the post on James River will in like manner be wintered at such points in Minnesota as General Sibley may designate. The steamers will carry supplies for all the troops operating under General Sully, both from his own district and from Minnesota, and General Sully is charged whit the duty of seeing that supplies for these troops, as well as the garrisons of the post at mouth of Long Lake and Devil's Lake, be delivered at the order post. He will also give the necessary instructions to the commander of the pos tat mouth of Long Lake to use all his exertions to forward the supply of the post at Devil's Lake.

It is very desirable to establish the post designated on the yellowstone, if possible, this season, but of the practicability of this General Sully must judge at the proper time. It is essential to the rapid movement of cavalry that wagon trains do not accompany it, and it is accordingly recommended that pack-saddles be taken to the point on the Missouri at which the troops will concentrate, so that in marching from there pack trains may be exclusively used. the details for supplying the posts at mouth of Long Lake, at Devil's Lake, and on the Yellowstone, as well as the troops engaged in military operations, ave placed in charge of General Sully, who will give every necessary instruction ont eh subject. Before he returns to Sioux City after the close of the military operations, General Sully will visit the post at mouth of Long Lake and satisfy himself that the garrison at Devil's Lake has been properly supplied for the winter, and that all needful preparations have been made for the comfort of the troops at mouth of Long Lake and for the care of the public animals to be sent there from Devil's Lake.

A sufficient number of horses and mules will be kept at Devil's lake and at the post on James River for express and other purposes. Well-marked trails should be opened as soon as practicable between all these posts, and the communication between the posts