Military Messengers have been employed in war since ancient times and still constitute a valuable means of communication.
Alexander, Hannibal, and Caesar each developed an elaborate system of relays by which messages were carried from one messenger post to another by mounted messengers traveling at top speed.
The first application of the telegraph in time of war was made by the British in the (1861–65), wide use was made of the electric telegraph.
In addition to its employment in spanning long distances under the civilian-manned military telegraph organization, mobile field service was provided in the Union army by wagon trains equipped with insulated wire and lightweight poles for the rapid laying of telegraph lines.
Before the end of the 18th century European armies used the visual telegraph system devised by towers or poles with movable arms.
Early signaling between naval vessels was by prearranged messages transmitted by , lights, or the movement of a sail.
Codes were developed in the 16th century that were based upon the number and position of signal flags or lights or on the number of cannon shots. In his successful demonstration of electric communication between Washington, D.
In the 17th century the British admiral and others developed regular codes for naval communication; and toward the close of the 18th century, Admiral Richard Kempenfelt developed a plan of flag signaling similar to that now in use. C., and Baltimore in 1844, he provided a completely new means of rapid signal communication.
This was probably due to the fact that the compelling stimulation of war was not present and to the fact that the development of long-distance telephone communication was not achieved for many years. Near the close of the 19th century, a new means of military signal communication made its appearance—the wireless telegraph, or .
The major powers throughout the world were quick to see the wonderful possibilities for military and naval signaling.