The main object of organizing troops in the western theater of war into military departments and placing them under your orders is to give you the general military control and at the same time to relieve you from the burden of official correspondence and office duty. If the whole were organized into a single department under your immediate command, your time would be mostly taken up with the details of courts-martial, furloughs, discharges, &c., while the present arrangement enables you to give your full attention to military operations.

In regard to General Banks' campaign against Texas, it is proper to remark that it was undertaken less for military reasons than as a matter of State policy. As a military measure simply, it perhaps presented less advantages than a movement on Mobile and the Alabama River, so as to threaten the enemy's interior lines and effect a diversion in favor of our armies at Chattanooga and in East Tennessee. But, however this may have been, it was deemed necessary as a matter of political or State policy, connected with our foreign relations, and especially with France and Mexico, that our troops should occupy and hold at least a portion of Texas. The President so ordered, for reasons satisfactory to himself and his cabinet, and it was, therefore, unnecessary for us to inquire whether or not the troops could have been employed elsewhere with greater military advantage.

I allude to this matter here, as it may have an important influence on your projected operations during the present winter.

Keeping in mind the fact that General Banks' operations in Texas, either on the gulf coast or by the Louisiana frontier, must be continued during the winter, it is to be considered whether it will not be better to direct our efforts for the present to the entire breaking up of the rebel forces west of the Mississippi River, rather than to divide them by also operating against Mobile and Alabama. If the forces of Smith, Price, and Magruder could be so scattered or broken as to enable Steele and Banks to occupy Red River as a line of defense, a part of their armies would probably become available for operations elsewhere.

General Banks reports his present force as inadequate for the defense of his position and for operations in the interior, and General Steele is of opinion that he cannot advance beyond the Arkansas or Saline, unless he can be certain of co-operation and supplies on Red River.

Under these circumstances it is worth considering whether such forces as Sherman can move down the Mississippi River should no co-operate with the armies of Steele and Banks on the west side.

Of course operations by any of your troops in that direction must be subordinate and subsequent to those which you have proposed for East and West Tennessee. I therefore present these views at this time merely that they may receive your attention and consideration in determining upon your ulterior movement. If we can rely upon what we see in the rebel newspapers and hear from spies and refugees from Richmond, the enemy's directing his attention particularly to the defense of Georgia, in anticipation that your spring campaign will be directed on Atlanta. In order to compensate for the loss of the Virginia and East Tennessee Railroad, and for the possible capture by us of some point on their main Atlantic route by Weldon and Charleston, the rebel government is working with great diligence to complete the road from Danville, Va., to Greens-