Before the Battle of Gettysburg in July of 1863, the Middle Department, the Eleventh Corps, the First Corps, and a few brigades of the Third Corps all had occupied the various mountain gaps of the old South Mountain battlefield. General Joseph Hooker who was in command of the Army of the Potomac ordered communication and observation posts to be established in order to visually see where the Confederate army was located at in the Cumberland Valley as they marched toward the Mason & Dixon Line.
On June 28th, General George G. Meade was promoted to commanding General of the Army of the Potomac. Upon receiving word of his promotion, General Meade, dissatisfied with the layout of the Union army, ordered his army to concentrate around Frederick before marching northward. This left the garrison at Harper’s Ferry, which had already evacuated to Maryland Heights, and the Middle Department to guard the areas of South Mountain and Frederick while a major battle was occurring in Pennsylvania.
After the Battle of Gettysburg, the Confederate army began it’s withdraw on July 4th. By July 7th, the Army of the Potomac was marching southward toward Frederick and the Catoctin Mountain. The weather was poor, leaving many Union soldiers exposed the elements. Prior to General Meade’s Army of the Potomac marching southward to pursue the Confederate army, General William French was ordered to reinforce the various gaps of the South Mountain battlefield.
By July 7 and 8th, as general headquarters were being moved to Middletown, signal stations and observation posts were in the initial phases of being established at Crampton’s Gap, Middletown, Boonsboro, Turner’s Gap and Washington Monument. As the signal officers moved on toward South Mountain, several points of communications were established by telegraph.
Early in the morning of July 8th, Captain Nahum Daniels ordered Captain Ernst A. Denicke and Lieutenant C. F. M. Denicke to observe movements in the Cumberland Valley from Washington Monument. Captain Daniels also ordered the signal corps officers to procure a detail of men to cut away timber that may obstruct the view near Washington Monument. Due to the recent rains, this task proved to be very difficult. As pioneers worked, sounds of battle were heard near Boonsboro, and by 10:00 am, the Washington Monument signal station was operational. During the Battle of Boonsboro, signalists at Washington Monument communicated with several other stations that were established.
Lieutenant Swain opened a station on the hill at Boonsboro directly in front of the Washington Monument. Lieutenant Briggs opened a station four miles south from Boonsboro at Elk Ridge. By 11:00 am, Elk Ridge communicated with Washington Monument, relaying information to the battlefield. During the afternoon, the signalists were sending messages throughout the valley. Washington Monument communicated with Boonsboro, as well as Elk Ridge. During the Battle of Boonsboro, the Washington Monument signal station proved to be invaluable.
Messages were being sent to Boonsboro, where many of those signalists reported that they were under fire. By 3:00 pm Captain Daniels had received information that they were unable to communicate with Frederick, and he ordered Lieutenant Denicke to assist Lieutenant Galbraith at Turner’s Gap in opening communications.
A day later, on the 9th, stations and posts were also established on Maryland Heights, and at Black Rock. However, the Washington Monument and other signal stations in the area were unable to communicate due to the hazy conditions.
The next day, as headquarters for the Army of the Potomac moved toward Beaver Creek, communication was again opened from general headquarters through Washington Monument. Several attempts were made to communicate with Washington Monument, however, from 8:30 am until 10:00 am there was no reply. Torches were also used at night at Washington Monument. At around 3:30 am, Captain Norton had ordered the station at Washington Monument to send a message to Elk Ridge ordering them to open communications with Bakersville.
By July 14th, the Washington Monument signal station was ordered to cease its operations. The Confederate army, under the cover of night, had already crossed into West Virginia near Falling Waters. Although, their work at Washington Monument was finished, Captain and Lieutenant Denicke were ordered to report to General Benjamin Kelley at Hancock.