In 1861 he entered the military telegraph service and was assigned to the headquarters of General Irvin McDowell in Arlington Heights, Virginia.
During his tenure with the United States Army, Emerick worked in the field headquarters of Generals Ambrose Burnside, Joseph Hooker, and George Meade.
Emerick was one of twelve military telegraphers who were awarded watches, presented by Edwin M. Stanton, Secretary of War, "in recognition of long and continued faithful service."
The watch together with the letter which accompanied it were among the most coveted of the telegrapher's mementoes of the American Civil War.
He was noted as a fine worker in his field, especially adept in sorting out the many details of the large telegraph system.