HEADQUARTERS DEPARTMENT OF THE MISSOURI,
Saint Louis, December 30, 1862.

Colonel N. P. CHIPMAN, Helena:

COLONEL: I wrote General Gorman yesterday, and sent the letter by colonel Vandever, who may get ahead of Lieutenant Stimpson, who will carry this.

The river must be kept open, if possible. Grant and Sherman seem to have drawn off their forces so far that others must attended to the rear. It may create great disaster in my command and elsewhere, but we must only took to the necessities of the occasion. Sad havoc has been made with the railroad, and now the river is threatened. If necessary and possible, General Gorman must assist Memphis or any other point where our line of communication is in danger, deferring, if need be, all interior operations from Helena till we are re-enforced by Grant or other arrivals on the river.

Thompson, Jeffers, and others, with a force estimated at 5,000 or 6,000, are in Stoddard County, Missouri, and General Davies has ordered New Madrid, given up, destroying guns and magazine. The only redeeming affair is the daring dash of Blunt and Herron on Van Buren, the full particulars of which you will receive from the papers of to-day. The Army of the Frontier will have to fall back for supplies, and wait till we can get strength enough to move up the rivers of Arkansas and hold them. If we can move directly up the Arkansas, of course that is best, and on paper one would so decide. I have no choice in the routes, only to carry out my objects, which are, first, to form junctions of forces north of the Arkansas River, thereby showing to the enemy he has no chance of taking my detachments, and give us quiet possession in Northern Arkansas; second, to secure convenient lines of communication interior from Helena, where we must keep supplies for interior posts.

The practical difficulties are on any interior route; and those on the Arkansas are these (I served a military apprenticeship on that river, and understand them):

1st. The Arkansas is so fickle, up to-day and dry to-morrow, it can hardly be called a navigable stream, especially for gunboats.

2nd. The fort at Old Post may check transports till the river falls. It is near the mouth, and no junction could be formed there, either with in near the mouth, and no junction could be formed there, either with Blunt's or Davidson's forces. Going right forward, as you suggest, may not be so easy. Yet it would be if we strong gunboat aid to take Old Post, and the water would hold up.

3rd. While such forces are on the lower trunk of the Arkansas, they do not support Helena, and Helena does not support them whereas forces moving direct west from Helena make closer connections.

All commercial men say the White River is the main dependence and surest stream for permanent connections with interior Arkansas, so that whatever we may do temporarily on the Arkansas River, we must also arrange to hold White River and the railroad from Devall's Bluff, as the safe means to supply posts at Little Rock and above.

I am sending small boats to accommodate any move necessary either up and down the Mississippi or up the Arkansas or White, as the general may conclude under my orders. It will be best for such boats to protect the pilot-house and boilers with plank or something else. A little precaution in this way costs very little, and may save a boat. I am glad to know the general cordially supports me. The tone of official correspondence from Washington is now all kind enough. I have not yet had time to ask explanation of the General-in-Chief concerning his