THE SIEGE OF YORKTOWN.
Our forces were in this position when in headquarters camp No. 1, near Yorktown, it wa first made known that the corps commanded by Major-General McDowell had been withdrawn from the Army of the Potomac. The hope felt by many that this corps was in some way to turn the enemy’s defensive lines at Yorktown fell. At the same time reports were received of reconnaissances made along the lines in front. Earthworks seemed to be found everywhere, and everywhere bodies of the enemy, vigilant and of unknown numbers, resisted any threatened assault. There were heavy rains, and the mud grew deeper. A siege was becoming inevitable.
On the 10th of April headquarters camp moved to Camp Winfield Scott, in front of Yorktown. At about this date the army corps commanded by General Sumner arrived. The signal detachment, commanded by Lieut. N. Daniels, acting signal officer, accompanied this corps. In the bay below Yorktown, at an estimated distance of from 3 to 4 miles from headquarters camp and in sight, lay the co-operating fleet, of which the United States ship Wachusett was flag-ship. From the shore of this bay southerly to nearly the bank of the James River the Army of the Potomac was stretched, buried in thick woods, and so hidden that rarely could more than a division be seen together, and often not more than a regiment was visible from any one point of view. The rebel lines reached through a light country from the works of Yorktown proper to nearly the navigable waters of the Warwick River. To pass from the right to the left of our lines, following the narrow and winding earth roads and the miles of corduroyed ways through the woods was a journey of several hours, during which one came by surprise, as it were, upon regiments and brigades of soldiers encamped here and there in the forests, and batteries of heavy field artillery in position among trees and shrubs, and bearing often upon an enemy whose lines and forces, hidden by other trees and shrubs, were invisible. Along all this line there was the picket firing of both musketry and artillery.
On the right, between the works at Yorktown and the fleet below, desultory shots of enormous weight were thrown to and fro from rifled ordnance and 11-inch guns. On land, along the front, if a venturesome picket or curious signal man of either army showed himself within gunshot, or climbed a tree for observation, he was fired at as game. If a group was gathered together anywhere it was customary to disperse it with a shell from a rifled gun. The appearance of an  officer with a telescope, or with any instrument of reconnaissance, rarely failed to elicit this attention.
On the left the rebel gunboat Teazer would now and then creep up the Warwick from the James River and try the ranges of her heavy guns upon the points where her commander supposed our camps might be. With the exception made by the opening of the trenches and the placing of our siege batteries (only one of which ever opened fire), this state of affairs was without change throughout the siege. There were some skirmishes, occasional artillery duels, and the affair of the Burnt Chimneys, or Lee’s Mill.
Scattered along this advanced line were the stations of the signal officers, and their duties brought them every day upon and near it. It thus happened to them, serving in their turns in front, that so many of their number came to be at different times during the siege exposed to the enemy’s sharpshooters, or, what was by far more common, to the fire of his artillery. Wherever stations were known or supposed to be the enemy day after day directed practice shots, either with guns from their batteries, or, as it once or twice happened, with lighter pieces brought for the Purpose.
In the list of officers whose names I had the honor to lay before the general commanding in my report of June 26, 1862, there is, I believe, no one who was not at some time during the siege exposed and near the enemy. The courage and persistence with which some of these officers held the posts to which they were ordered (though in danger day and night for a week together) was worthy of commendation.
Official Records of the Rebellion: Volume Eleven, Chapter 23, Part 1: Peninsular Campaign: Reports, pp.228-229
web page Rickard, J (19 November 2006), http://www.historyofwar.org/source/acw/officialrecords/vol011chap023part1/00012_05.html