HEADQUARTERS CHIEF ENGINEERS OF DEFENSES, Washington, October 14, 1863.

Honorable E. M. STANTON,
Secretary of War:

SIR; A Commission having been ordered by you a year ago, to examine into the system of the defenses of Washington, and that report having received your approval, I feel it proper to make a brief statement of teh operations on the works and their condition.

Previous to my resumption of charge of these works in August, 1862, the system was but a skeleton, so to speak, of a fortified line. In many important parts, indeed, though the works would be valuable as points-d-appui to a line of battle, they would be almost useless unless in connection with an army strong enough to be capable of giving battle. Washington required something more than this. Washington required to have all the strength that could be attained from a line of field-works; a strength which would enable it to be defended with a moderate force against very superior numbers, at the same time furnishing to an inferior or defeated army, forced to take refuge within its lines, an impregnable barrier. In accordance with this idea, I immediately commenced operations, which were approved and confirmed by the commission. I give a brief sketch.

Fort Lyon. -Four out-works, Forts Willard, O'Rorke, Farnsworth, and Weed, have been completed and armed, and auxiliary batteries and rifle-pits connect them. The position now is a very strong one.

Fort Williams. -One Traitor's (Cooper's) Hill, has been built, also rifle-pits and batteries between it and Ellsworth. With a few pieces of field artillery in these batteries and the opposite one near Fort Lyon, and some watchfulness, a cavalry raid into Alexandria would be difficult, while they complete the system of defense against regular attacks.

Battery Garesche, a small fort, has been built near Fort Blenker. It is armed and efficient.

Fort Berry, occupying an important point between Forts Barnard and Richardson, has been built and armed.

Fort Whipple. -This powerful work, one of the finest field-works in teh world, was commenced in teh spring, and had its batteries ready early in June. It is now essentially complete.

Fort C. F. Smith, commenced last winter, was in readiness early this spring. It is a powerful work, and is essentially complete.

The various works on the line south of teh Potomac, from Fort Lyon to Fort C. F. Smith, have, with few exceptions, undergone important modifications and improvements.

In Forts De Kalb, Craig, and Tillinghast, large bomb-proofs have been made (all the new works, except Berry, have extensive bomb-proofs), and in all, new embrasures and platforms have been made, magazines strengthened, &c. The works have been connected by rifle-pits (more properly covered ways for infantry), and at all points where artillery could be advantageously used, batteries for field guns have been constructed.

Forts Ethan Allen and Marcy (at Chain Bridge). -These works have been extensively repaired and improved, and large additional bomb-proofs built. They are connected and supported by covered way rifle-pits, and batteries for field guns arranged where necessary.