Numbers 2. Reports of Brigadier General John G. Barnard,

U. S. Army, Chief Engineer of operations from May 23, 1861, to August 15, 1862.

Washington, January 26, 1863.

GENERAL: In compliance with the request of Major-General McClellan, I make the following report of the engineer operations of the Army of the Potomac executed under my direction as chief engineer of that army from the time of its organization to the date at it was withdrawn from the James River:

On the night of the 23d-24th of May, 1861, a portion of the force which had been raised under the different calls of the President for three-moments' and three-years' volunteers crossed the Potomac by the Long Bridge, by the Aqueduct Bridge, and by steamers Alexandria, seized the city of Alexandria, the heights of Arlington, and intermediate connecting points. As tetes-de-pont to the Long Bridge and Aqueduct, Forts Runyon and Corcoran (the sites of which had been previously reconnoitered under my direction) were commenced at daylight on the morning of the 24th. The same day a reconnaissance was made in the vicinity of Alexandria by Captain Wright, Engineers (now major-general U. S. Volunteers), and Fort Ellsworth, to secure our possession of that city, was commenced. A couple of weeks later I laid out Fort Albany (intended to command the Columbia turnpike and the Aqueduct and Alexandria roads, and to give greater security to our debouche by the Long Bridge), which was commenced under Captain Blunt, Engineers.

These works were all considerable magnitude (Fort Runyon having a perimeter of 1,500 yards). They were not entirely completed, though very nearly so, and quite defensible at the date of the advance of the army under General McDowell, July 16. I give this brief account of these preliminary works because they formed the imitation of the system of the defenses of Washington.

On the return of the army from the campaign of Bull Run the policy of surrounding Washington by a complete system of defensive works was no longer doubtful. Major-General McClellan, on his assumption of the command of the Army of the Potomac, was prompt to recognize the necessity of further fortifications, especially urgent at that time. In as rapid succession as possible, and in the order of the most urgent importance, new works were commended. The interval between Fort Corcoran and Fort Albany was filled by a series of works forming a continuous line within supporting distances, protecting the height of Arlington. At the same time the most prominent points on the north of the Potomac and those controlling the important routes leading to the capital were occupied by strong works.

It was soon apparent that Fort Ellsworth, important as that work still is, was inadequate for the defense of Alexandria. It was found necessary to occupy with a powerful work the height over Hunting Creek, and form a line of works embracing the Seminary Heights, and connecting with our Arlington lines at Fort Albany.

About the middle of September a portion of the army crossed the Chain Bridge and occupied the south shore of the Potomac at that point. The same night strong works, the site of which had previously been reconnoitered by Major (now Brigadier-General) Woodbury, were commenced for holding this debouche.

On the 29th September (I think it was the army advanced to the