more surely reached by an interior line of operations behind and east of the Blue Ridge, at the same time covering Washington, our proper base, and threatening the enemy's communications, compelling him thus to evacuate the vicinity of Herper's Ferry; in which event field defenses, with a moderate garrison, would suffice to hold that point against any probable attack to be made upon it; and the permanent railroad bridge, now being built, would suffice for all our wants, without the one proposed to be erected by General McClellan about 1 1/2 miles above.

H. W. HALLECK,

General-in-Chief.

OCTOBER 20.

Submitted to the Secretary of War, and approved by him.

H. W. HALLECK.

HARPER'S FERRY, VA.,

October 17, 1862-9 a.m.

Colonel A. BECKWITH,

Commissary of Subsistence:

It would be entirely impracticable to receive stores by the canal. This depot is on the Shenandoah, and on this side of the Potomac, and over a mile from the Potomac, while the canal is on the other side of the Potomac, and alongside of it, and to get wagons to haul supplies from there over the pontoon bridge would be impossible.

THOS. WILSON,

Captain, &c.

WASHINGTON, October 17, 1862.

Captain RICHARD B. IRWIN,

Assistant Adjutant-General:

CAPTAIN: To defend the Chain Bridge against a vigorous assault of an enemy in force would require about 8,000 men, or, rather, that would be a feull and satisfactory number, a less one-say 5,000 or 6,000-being able to hold the position for some time.

The above includes garrisons of works. It is always difficult to say how much this number may be reduced. If the enemy is in force in Northeastern Virginia, and we have no force between him and our lines, it is evident that we should keep the garrison so near the above number that reserves near at hand can fill it up at a few hours' notice.

The question frequently comes up, how many men are required for the defense of Washington? I answer that Washington is not a simple fortification, whose garrison is estimated according to certain fixed rules, always implying that the fortress is attacked by unlimited numbers. Washington is an enormous intrenched camp, having a perimeter of 35 miles to hold. The number required to hold it would depend upon the number by which it is attacked.

The commanding general of the active forces in Virginia would always be the best judge of how many men are required in Washington, and it is for want of harmony and concert between those who controlled the forces near Washington and the commanding general of our principal active army that we owe in part recent disasters.

The general commanding in the field may so maneuver as to keep himself between Washington and the bulk of the enemy's forces, or he