their headquarters were in the vicinity. When General McClellan took his position upon the field of battle, the headquarters station was that,then near him, which had previously been established near General Pleasonton.

With the advance of General Jesse Reno's division to the crest of the mountain south of the gap, a signal station was ordered, as I am informed by Captain Fisher, to be located upon the crest. Owing to some conflicting instructions from some officer, this station was not established. Later in the afternoon Lieuts. J. C. Paine and C. H. Carey were directed to open a station at this point. The flag was promptly carried to the position indicated, and the communication opened with both the station of observation on the

tower and a station near General McClellan, then on the field. A few reports were received from this station, but it was feebly worked, soon ceased to reply to calls, and became of no importance. At noon the whole line of communication mentioned was fully opened, and during the progress of the engagement there were given to General McClellan on the field reports from Point of Rocks, Sugar Loaf Mountain, and the other stations established. There were announced, among other reports, the movements of our troops visible in the valley and on the ridge, and at the time of their occurrence the facts of General Franklin's engagement, then commencing at the gap near Burkittsville, the sounds and smoke as of a battle of Maryland Heights, and that no enemy was visible anywhere on our left of in the valley of the Potomac. A message wa signaled from the field, addressed to General H. W. Halleck, at Washington. The stations were fully employed throughout the engagement until night. Some of Them had been working form early morning. The officers remained at their posts throughout the night. There were,however, no occasions for night signals. At daylight on the following day it was found that the retreat of the enemy had rendered the further occupation of those upon and near the battle-field unnecessary.

On Monday, September 15, following the retreat of the enemy, commenced the advance of the army through the pass in South Mountain and toward the Antietam. Early in the morning the course of the enemy's retreat and the positions they would select were uncertain. Officers were sent to the summit of the Blue Ridge with instructions to select stations, and also to examine and report their observations of the country upon the west side of the Blue Ridge. A careful examination was made from the high peak of the Blue Ridge north of the gap known as Washington monument, which overlooks all the valley between the North and South Mountains.

From this point the forces of the enemy were visible near Sharpsburg, and thence to Shepherstown. The line of battle beyond Antietam, then just beginning to be formed, was seen, and a full report of this and other facts sent to General McClellan. The line was yet forming as this dispatch was forwarded by orderly. It is possible it contained as early information as any given as to the position of the enemy. A signal station was established at this point.

On the evening of this day it became evident that there would be an engagement of some magnitude, and preparations were commenced for the battle of Antietam. At this time and early on the following morning instructions were received from General McClellan that signal communication should be established between his position chosen for the field of battle to so far as practicable on the right and left within

our lines; that our left should be observed with particular care, and