Fitz John Porter, director of the siege, to whom was assigned the guarding of the trenches, the assembling and distribution of the working parties,&c.

Early in the morning of the 14th, upon the enemy's abandoning has lines at Yorktown, I ordered all the available cavalry force, with four batteries of horse artillery, under Brigadier-General Stoneman, chief of cavalry, in immediate pursuit, by the Yorktown and Williamsburg road, with orders to harass the enemy's rear and try to cut off such of his forces as had taken the Lee's Mill and Williamsburg road.

General Heintzelman was directed to send Hooker's division forward on the Yorktown and Williamsburg road to support General Stoneman, and Smith was ordered to proceed with his division on the Lee's Mill and Williamsburg road for the same purpose. Afterward the divisions of Generals Kearny, Couch, and Casey were put en route, the first on the Yorktown road and the others on the Lee's Mill road. These roads unite about a quarter of a mile south of Fort Magruder, and are connected by cross roads at several points between Yorktown and Williamsburg. After these directions had been given General Sumner (the officer second in rank in the Army of the Potomac) was ordered to proceed to the front and take immediate charge of operations until my arrival.

General Stoneman moved forward promptly with his command, consisting of four batteries of horse artillery, under Lieutenant-Colonel Hays, the First and Sixth United States Cavalry, the Third Pennsylvania, and Eighth Illinois, and Barker's squadron, meeting with but little opposition until he arrived in front of the enemy's works about 2 miles east of Williamsburg.

At a point about 8 miles from Yorktown, in accordance with my instructions, he detached General Emory, with Benson's battery the Third Pennsylvania Cavalry (Colonel Averell), and Barker's squadron to gain the Lee's Mill road, and endeavor, with the assistance of General Smith, to cut off the portion of the enemy's rear guard which had taken the route. General Emory had some sharp skirmishers with a regiment of cavalry and a battery under General Stuart, and drove them in the direction of Lee's Mill.

General Smith, having met with obstructions in his front, had transferred his column by a cross road to the Yorktown and Williamsburg road, so that General Emory, finding no force to

co-operate with him, was unable to cut off the rear guard, and they succeeded in escaping by a circuitous route along the bank of the James River.

The position in which General Stoneman encountered the enemy is about 4 miles in extent, the right resting on College Creek and the left on Queen's Creek, nearly three-fourths of its front being covered by tributaries of these two creeks, upon which there are ponds.

The ground between the heads of the boundary streams is a cultivated plain, across which a line of detached works had been constructed, consisting of Fort Magruder, a large work in the center with a bastion front, and twelve other redoubts and epaulements for field guns.

The parapet of Fort Magruder is about 6 feet high and 9 feet thick, the ditch 9 feet wide and 9 feet deep, filled with water. The length of the interior crest is about 600 yards. The redoubts have strong profiles, but are of small dimensions, having faces of about 40 yards. The woods in front of the position were felled and the open ground in front of the works was dotted with numerous rifle pits.

The roads leading from the lower part of the Peninsula to Williamsburg - one along the York River (the Yorktown road) and the other