BATON ROUGE, LA., December 28, 1864.

Major General JOSEPH J. REYNOLDS,

Commanding Department of Arkansas, Little Rock:

GENERAL: I was unable to procure any maps of the localities of Devall's Bluff and saint Charles, on the White River, either at Little Rock or of the commanders of those posts. I am, therefore, obliged to make use of the most general terms in stating what I deem essential in arranging the defenses of those places. It must be admitted that White River, being the only line that can be relied upon throughout the year for supplying Little Rock and other posts in the interior of the State, not excepting Pine Bluff, rises to considerable importance.

Devall's Bluff: I made a somewhat careful examination of the ground about Devall's Bluff, and am of the opinion that the three works proposed by Captain Wheeler, of the U. S. Engineer, who accompanied me in the examination, are judiciously located. There is an elbow in the river at this point convex toward Little Rock, where the bluffs approach near to the river. The bank, on the opposite side of the stream, is low and flat. The same is true of the Devall's Bluff side above and below the landing. There are three prominent and commanding hills (the two extreme ones being, I should judge, from 1,100 to 1,200 yards apart in a straight line, and each distant about 600 to 700 yards from the third or intermediate hill), which, from their relation to each other and to the ridges and ravines within gun-range, offer good positions for strong inclosed works. These works should each be designed for a garrison of 250 to 300 men; they should have a strong barrier at the entrance, and be surrounded with a formidable obstacle under close musketry fore from the parapet. One of these works is now being constructed on a very good plan. As the ranges are not great, in consequence of the peculiar configuration of the ground, the armament should consist in part of pieces most suitable for searching the ravines with shells and spherical case-shot. Three or four siege or large field howitzers in embrasure, or between high traverses, with additional embrasures for lighter guns, so that three or four pieces can be brought to bear on each of the principal approaches, would be sufficient for each work. An infantry parapet, arranged with positions for light batteries at suitable points (much of which is already completed), should connect the extremes of this line. In case Devall's Bluff should become an important depot, which is not improbable (it being a point where supplies change from water top land transportation), three or four additional inclosed works of small capacity, on the summits of hills in advance of those already mentioned, would add greatly to the security of the depots from shelling. The entire system of works should be mutually defensive as far as practicable, and they should each be sufficiently strong to withstand an open assault on any and every side.

Saint Charles: At Saint Charles (on the right bank of White River, eighty-five to ninety miles below Devall's Bluff) a field-work has been partially constructed open to the river, with its flanks resting on the river-bank. The development of the line, as ascertained by pacing, is about 630 yards in length. The distance in a right line between the flanks is about 200 yards. The work is not surrounded by any obstacle except the ditch, which could be easily passed by an assaulting column unless prevented by the fire from the works. One section of 12-pounder Napoleons is the only artillery in the work or at the post. One six-gun battery would not be too great an armament for such a work, which, however, is larger by half then the position would seem to require, so long as we hold Bluff with an adequate force, and