these batteries above the water-line for accuracy of firing, the guns of the two works do not afford sufficient reliable fire as would insure the checking of an attempt to pass the batteries. I would, therefore, recommend that these two works be furnished with the full armament for which they are constructed and that they be manned by efficient artillerists. The works on the north side of the Potomac are a continuous line of forts from Fort Sumner, on the river above the city, to Fort Greble, on the river below the city. The forts in this line are in artillery support of each other, and connected throughout by earthen epaulements. Fort Gaines is an interior work. The most important position of this line is that part included between Forts Sumner and Slocum as it covers the approaches to the city on the river line of roads. The most important works in this portion of the line are Forts Stevens, Reno, Sumner, and Slocum. The portion of the line between Fort Slocum and the Eastern Branch is less liable to be assailed, and that portion of the line east of the Eastern Branch the least liable to attack of any part of the whole defenses. The most important works between Fort Slocum and the Eastern Branch are Forts Lincoln, Bunker Hill, and Totten.

The most important works east of the Eastern Branch are Forts Stanton, Carroll, and Greble which, from their position, are in range of the Arsenal and Navy-Yard, and Fort Stanton in easy command of both. With a view to guard these works from a surprise, I recommend that regiments of the Reserve Corps be stationed at the following points: One regiment between Forts Sumner and Mansfield, one regiment near Fort Reno, one regiment near Fort Stevens, one regiment between Forts Slocum and Totten, one regiment between Forts Lincoln and Bunker Hill; the officer commanding the division north of the Potomac to establish a picket-line from this force. The cavalry at the fords of the Potomac, beginning at Great Falls and extending to the Monocacy, is sufficient, as is the force on the south side to guard the railroad. The forts throughout the line are advanced to completion, sufficient for defensive purposes, except Forts Ward and Stanton, in which I found but few guns mounted, and the work on them progressing but slowly.

The guards at the different bridges I think have been insufficient, and the guard duty generally loosely and carelessly performed. This has arisen in some degree from the guards being composed of detachments of companies and commanded by non-commissioned officers. I recommend that the following changes be made in the guards at the bridges: One full company at Fort Jackson, at the head of Long Bridge, one full company at the new stockade at the head of Aqueduct Bridge; one full company at the Georgetown head of the Chain Bridge, with a guard of 10 men and 2 non-commissioned officers from this company at the iron gates of the bridge; one platoon of a company at the Navy-Yard bridge, and the other platoon of the same company at the upper bridge of the Eastern Branch. The performance of the guard duty as required by the regulations of the service should be rigidly enforced. There is no communication between the forts by signal, nor between the outside and the forts. Signals are made from the outside of the works directly to department headquarters and from thence to headquarters of the division south of the Potomac by telegraph. I recommend that signal communication be had between the outside and the forts, and between the forts. The roadways within the line of defenses are ample and sufficiently good for practical purposes.