and very active, while deserters stated that the troops at Yorktown, originally about 15,000, had been vastly increased by arrivals from Richmond, and were confident of successfully defending the place. On this end of the line it was at this time well established that the works could not be carried before the enemy's artillery was silenced without fearful sacrifice of life, while I understood that in the opinion of the general commanding the left, as well as of the engineer officers, the line of the Warwick below Wynn's Mill could not be carried by assault.

Heavy rains having rendered impassable the roads to the depots for subsistence, I caused to be examined and staked out the channel of Wormley's Creek, with the view of getting provisions and grain landed in my camp. Up this creek was eventually brought the pontoons and also the heaviest portions of the siege artillery. For ease of communication, and to enable support to be thrown, if necessary, quickly to the front, I caused bridges to be thrown over this creek and roads to be opened, and for annoyance to the enemy and the security of the picket line along the whole front of the corps I caused to be detailed daily portions of the regiment of Sharpshooters under Colonel Berdan, who, aided by Lieutenant-Colonel Ripley and other officers of the regiment, pushed the rifle pits as close as possible to the enemy's works. The Berdan Sharpshooters throughout the siege also furnished companies and rendered valuable aid to the corps of Sumner and Keyes.

The troops were employed to the 17th, in connection with those of other divisions of the corps, in opening roads, building bridges, guarding the front, and in occasional reconnaissances. On the 11th the enemy, after driving in the pickets of Hamilton's division and destroying the house in the peach orchard to the left of the Yorktown road, attacked my picket line, but was repulsed by a section of Weeden's Rhode Island Battery and the Twenty-second Massachusetts Volunteers, under Lieutenant-Colonel Griswold. My picket line was immediately re-established, but Hamilton's did not connect till the 17th under Colonel Lansing. On the 13th an attack on the right of my line, was handsomely met and repulsed by the Twelfth New York Volunteers, under Major Barnum. A close and thorough reconnaissance on the 25th, made by that excellent officer of the army, Colonel Jesse A. Gove, with his regiment, the Twenty-second Massachusetts Volunteers, confirmed his former reports of the 5th and 16th that the Warwick was not fordable, the banks swampy, and the dams near its headwaters, on account of artificial obstructions, unapproachable in face of the enemy on the opposite banks. The reports of casualties in these affairs have been forwarded, as well as the result of the re-connaissance.

Reconnaissances in the balloon had materially aided me, as well as other officers, in obtaining information of the strength of the enemy's position, which was to a great degree confirmed on the 11th by an elevated and extensive view of the defenses of Yorktown, the whole line of the Warwick, and of the enemy's bivouacs, obtained while accidentally breaking loose while ascending. I desire here to remark that the balloon can be made a most useful accessory to reconnaissances, and especially valuable in an extensive battle, if the observer be intelligent and educated for the military profession. Without that professional education the relations of works or bodies of troops to each other and the movements of troops or trains of artillery or wagons, and many other facts of the greatest moment, may and often will be unnoticed. A signal officer, or, better still, the magnetic telegraph, should accompany the aeronaut.

On the 18th of April, the necessary approaches to the first parallel