Numbers 19. Report of Brigadier General Fitz. John Porter,

U. S. Army, as Director of the Siege of Yorktown, from April 7-May 5.

DIVISION HEADQUARTERS, OPPOSITE WEST POINT, VA.,

May 8, 1862.

GENERAL: I have the honor to present the following narrative of events in front of Yorktown, connected with the operations of my division and my duties as director of the siege since my last report of the 7th of April:

To the 10th ultimo my division occupied the position in front of Yorktown taken on arrival, viz: One brigade in the timber skirting the upper branches of Wormley's Creek, one brigade in rear on the plateau immediately west of the mill-dam on that creek, the third brigade in the angle between the roads to Yorktown from Warwick Court-House and Fortress Monroe. Batteries were attached to each brigade, and posted to sweep all approaches and the front of each command. My command thus posted guarded the whole front of Yorktown from York River to the Warwick. Two brigades were shielded by timber from the view of the enemy and protected against sorties, and could give to or receive quickly aid from the other brigades if attacked. Sentinels were pushed as far to the front as the irregularities of the ground or other cover would permit, and, with the artillery behind a parapet erected for the purpose near the White House, inflicted, much injury upon the skirmishers and gunners and the enemy encamped within the works. The Fourth Michigan Volunteers in open day drove from under the guns of the enemy from 20 to 30 beef cattle and cows, and so quickly that the enemy could not fire upon them until they had secured their booty and were under shelter.

Our camps were within range of the enemy's guns, and consequently without fires, during the exceedingly wet weather of that period. I was therefore instructed by my corps commander to move on the 10th of April my division to the plateau south of Wormley's Creek, and to picket from York River to the Yorktown road, where they would be joined by the pickets of Hamilton's division, which at this time had arrived, and had been directed to relieve my brigade on the west of the Yorktown road. My division occupied this position till the close of the siege, the duties in front being diminished by Hooker's division, which arrived soon afterwards and encamped immediately on my left, thus closing the interval between Hamilton and myself, and completing the line from York River to the Warwick. While under the fire of the enemy's guns, so carefully and well posted were the men that from the 6th to the 10th of April the division lost only some 15 men, including casualties from several sorties from the enemy on the left; yet I have reason to believe more serious loss was inflicted upon the enemy.

Personal reconnaissances, confirmed by the reports of engineer officers and the troops, showed the Yorktown defenses to be strong and well armed, and connected with those on the Warwick by field works for artillery and infantry; that the Warwick was not fordable; that the bridges were destroyed, and the approached to the several dams, which had backed up the water to overflow the banks, were obstructed by abatis and defended on the right bank by strong forts, which were well armed and manned, and connected by infantry parapets.

Officers on picket reported the enemy apparently in great numbers