the position of the guns at Catoctin Pass, west of Frederick, was at once reported to General McClellan, near Urbana. The cannonade proved to be our advance attacking-the rear of the enemy. The pass was force about noon. Lieuts. N. H. Camp and G. J. Clarke, who had been so fortunate as to be with the advance, were, by direction of Captain Fisher, stationed at the summit of the pass, and in Communication with Lieutenant W. H. Hill. stationed with General Burnside in Frederick. Messages relative to the movements of the troops were received and answered. Lieutenants Camp and Clarke being relieved at this station, proceeded with the forces under General Pleasonton to Middletown. The attempt was made by Captain Fisher to connect with a signal line Middletown and Frederick. This, although easily feasible, failed in the confusion and change of camps. At about 1 p. m. signal reports from Sugar Loaf Mountain to the general commanding the army at Frederick announced that no enemy was visible or apparently near our left. Later in the afternoon signal reports from Point of Rocks stated that the enemy were in Pleasant Valley; that a portion of their forces had been visible at Jefferson, and that they had cut the canal at Knoxville, to be able, if necessary, there to cross the Potomac into Virginia. No news had been received direct from Harper's Ferry at any station. A heavy cannonade had been heard in that direction. In the evening a message was received from Washington, transmitted through the signal station at Point of Rocks, from the President of the United States to General McClellan. A reply was in the same manner returned. The line of signal communication extended on this day and night near Catoctin Pass. On this day Lieutenant F. N. Wicker took possession, on the summit of the ridge, of a rebel signal flag, which it is probable had been just used at one of their stations.

On Sunday, September 14, was fought the battle of South Mountain. It was the plan of the signal stations ordered this day that the general commanding the army should be enabled to receive on the field reports form the Valley of the Potomac by the stations at Point of Rocks and Sugar Loaf Mountain, and from Pleasant Valley by a station established on some commanding eminence in that valley. There would be thus information of any occurrences east of Catoctin Ridge or in the valley west of Catoctin Ridge on our right or left, or on the ridges which might be visible from these stations. It was also intended, as is customary, that signal officers should

accompany the advance of our troops when attacking the enemy's position, to communicate to the general commanding the field any information they might be able to gain at points from which it was possible to work stations in his vicinity. This part of the plan was not executed as well as was practicable, for the reason that no signal officer had early information as to the plan of attack. The stations at Sugar Loaf and Point of Rocks were maintained.

As the general movement form Frederick to the pass at South Mountain commenced, a station was ordered to be located on Catoctin Ridge, and to communicate thence with Sugar Loaf and with the prominent tower of a church in Middletown, which was selected as a station of observation for the valley. With the advance of our troops to the gap and the planting of our batteries, a station had been opened, under the supervision of Captain Fisher, at the battery bear General A. Pleasonton, communicating thence to the Tower station in Middletown. During the morning's cannonade messages were here received from the gap for Major General A. E. Burnside and for Major General G. B. McClellan, while