There are now upon our line between Point of Rocks and Hancock nine regiments and twelve guns devoted to this duty. The substitution of effective cavalry for a part of this force would allow it to be reduced, if necessary, to two regiments and six guns, with such a reserved force at a central point, say Hagerstown, as the strength and movements of the enemy should require. Inclosed you will please observe a schedule of troops, with their dispositions, cavalry and infantry, based upon the view I have presented. The infantry could not well be diminished except as to the reserve, which could be strengthened or reduced as circumstances should require; the cavalry might be increased at pleasure. Posted in small numbers, at convenient distances, some of the burdens of the service would be lessened, such as quarters, supplies, forage, &c., as they would make available the resources of neighborhoods, and the activity of their duties would preserve discipline and increase their strength, which in infantry is sometimes seriously impaired by similar service.

II. In regard to the dispositions of troops near Patterson's Creek:

It appears to me that a line what is called the South Branch of the Potomac, running parallel with Patterson's Creek, about 5 miles farther westward, is in all respects preferable to General Lander's position at the mouth of the creek. This offers little advantage except the protection of the road at that precise point, and places him at the disadvantage of having the river in his rear. If he follows the creek southward towards Burlington he puts the creek in his rear, as the road passes principally on the enemy's side. But upon the lien of the river between.

Paddytown and Cumberland he has communication in both directions by railway, highway, and river, which last is always between him and the enemy. In case of necessity communication is open to Piedmont, 4 miles westward, which is an impregnable position, taking advantage of the mountain pass, and conncestes by railroad, common road, and river with Cumberland, and westward with Wheeling by railway. This seems to be as stronger and more expansive position than any which Patterson's Creek affords, and equally effective for the protection of the road. I do not believe, however, that wing of the road can be protected so long as the enemy holds undisputed possession of Winchester and surrounding country. The reconstruction of the road, I think, should commence on the other wing, and follow or occupation of that country.

III. I am clearly of opinion that it is impracticable to reconstruct the Baltimore and Ohio Railroad while the enemy holds possession of all the country south of its line. He must be expelled either by a decisive contest on this line or on that in front of Washington. More recent evans have led me to believe that he will the reconstruction with all his power.

I have the honor to be, with great respect, your obedient servant,

N . P. BANKS,

Major-General, Commanding Division.

[Inclosure.]

Dispositions of troops on the Potomac between the mouth of the Monocacy and Sir John's Run, above Hancock.

UPPER DEPARTMENT.

Sir John's Run, one company cavalry.

Hancock, two companies cavalry, two companies infantry.