General Grant, and also your letter of the 10th instant upon the subject of the expedition into Texas.

I have made all possible exertions to get a sufficient force into the field to execute the order, but encounter serious difficulties in the preparation. General Ord's corps d'armee has not yet arrived. The last division will be here at the close of this week. The sickness and absence of officers delays seriously our preparations for movement.

There is very great deficiency of transportation for movement by water, either by sea of the river. The river boats sent up with the nine-months' troops are detained above, and return slowly. By the Gulf we are able to move, after all possible exertions, but one-third of our forces at once time. This is a serious misfortune, as it costs us most valuable time and gives the enemy opportunity to anticipate our plans and concentrate his forces against us. I hope, however, to be able to execute your orders without further material delay.

The considerations embraced in your letter of the 10th, duplicate copies of which I have received, have been carefully weighed. To enter Texas from Alexandria or Shreveport would bring us at the nearest point, Hemphill, in Sabine County, or Marshall, in Harrison, due west of Alexandria and Shreveport, respectively. These points are accessible only by heavy marches, for which the troops are illy prepared at this season of the year; and the points occupied would attract but little attention; and if our purpose was to penetrate farther into the interior, they would become exposed to sudden attacks of the enemy, and defensible only by a strong and permanent force of troops. The serious objection to moving on this department is the distance it carries us from New Orleans - our base of operations necessarily - and the great difficulty and the length of time required to return, if the exigencies of the service should demand, which is quite possible. In the event of long absence, Johnston threatens us from the east. The enemy will concentrate between Alexandria and Franklin, on the Teche,until our purpose is developed. As soon as we move any distance, they will operate against the river and New Orleans. It is true that we follow up such a movement by falling on their rear, but that would compel us to abandon the position in Texas, or leave it exposed with but slender defenses and garrison.

This view is based,as you will see, upon the impossibility of moving even to Alexandria, at the present low stage of the rivers, by water, and the inability of the troops to accomplish extended marches.

A movement upon the Sabine accomplishes these objects: First, it executes your order by planting the flag at a prominent and commanding position in Texas; secondly, it is accomplished by water; thirdly, it is safely made with a comparatively small force, and without attracting the attention of the enemy until it is done; fourthly, it enables us to move against Galveston from the interior, destroying at the same time all the naval and transport vessels of the State between the Sabine and the Colorado; fifthly, to occupy Galveston island with a small force of 2,000 or 3,000 only, and to push on to Indianola on the Rio Grande, or to return to the Mississippi, as the exigencies of the service may require. If the enemy moves in force upon New Orleans, we can return from Sabine or Galveston in such time and in such strength as to cut off his retreat by the bay on the Atchafalaya.

The advantage to be gained by the destruction of the rebel boats on the Sabine, in Galveston Bay, and on the Trinity and Brazos Rivers would be very great. This can be effected only by a movement upon