that from the most commanding points of view reports should be made of any information in regard to the battle. The station on Sugar Loaf was retained, to warn against any possible movement in that vicinity.

At 2 a. m. on September 16 orders were sent to Captain Fisher, in charge of the signal detachment then at Boonsborough, to bring the party forward as rapidly as practicable to near the Antietam. He was also directed to establish an officer of Washington Monument, the point above mentioned. The instructions of this officer were to report to the battle-field any movements of the enemy visible to him at any point in the valley, or clouds of dust, or signs of forces approaching or near the position held by our army. He was afterward instructed, by signals from the field during the progress of the battle at Antietam, to particularly notice any approach made in the valley behind the Elk mountains, which, bordering the Antietam, touch the potomac near the mouth of that creek. Additional instructions were given Captain Fisher upon his arrival at Keedysville.

At 10 a. m. there had been established on the field at Antietam a signal station communicating with the station on the monument, one on the left, on an elevation near the left of General A. E. Burnside's forces, which communicated with the station on Elk Mountain, and one on the right near General G. G. Meade. A station of observation had been previously established on the crest of Elk Mountain at the gap, afterward cut for the convenience of the officers there stationed, and now designated by the soldiers as "Mc Clellan's Gap."

The extensive view from this position commanded Sharpsburg and Shepherdstown, with very many points of the battle-fields, the approaches to it, and the country in the vicinity. A careful telescopic examination of all points thought to be of interest was made, and a full report of the enemy, then in front of Sharpsburg, and of such movements as were visible, was sent to

the general commanding. Officers were kept at their posts on this station by day and night, with but a few hours' interval, from the commencement of the battle until the retreat of the enemy beyond the Potomac. The station was worked with peculiar labor, it being necessary to observe at times from the top of a tree, while the signals were made from a point beneath among the branches, where the flagman could only sustain himself by exertion. All stations communicated with a central or headquarters station. From these points reports and messages of various value were transmitted throughout the day. The movement of the enemy which seemed most to attract attention, and which was twice reported-one from Washington Monument and once from the station on Elk Mountain-was the apparent motion of large trains from behind the woods west of Sharpsburg to Shepherdstown, and into Virginia.

In the afternoon the enemy's line of battle seemed to have changed from in front of Sharpsburg. About dusk that evening commenced

our attack upon their left. Lieuts. J. B. Brooks and W. H. Hill, ordered to move with Major General Joseph Hooker, commanding the right, skillfully located their station this night near his headquarters, and close to the Sharpsburg and Hagerstown turnpike, and were ready at this position at daylight.

On Wednesday, September 17, was fought the principal battle of the Antietam. The general plan of signal operations was similar to that of that preceding day, the reports from the station on the right and from the station on Elk Mountain being concentrated at what was known as the Headquarters station, near General McClellan. A station