Tactical communications

Tactical communications are military communications in which information of any kind, especially orders and military intelligence, are conveyed from one command, person, or place to another upon a battlefield, particularly during the conduct of combat. It includes any kind of delivery of information, whether verbal, written, visual or auditory, and can be sent in a variety of ways. In modern times, this is usually done by electronic means. Tactical communications do not include communications provided to tactical forces by the Defense Communications System to non-tactical military commands, to tactical forces by civil organizations, nor does it include strategic communication.

The earliest way of communicating with others in a battle was by the commander's voice or by human messenger. Someone would have to run from one commander to a subordinate to tell them what to do. Once the horse was domesticated messages could travel much faster. A very fast way to send information was to use either drums, trumpets or flags. Each sound or banner would have a pre-determined significance for the soldier who would respond accordingly. Auditory signals were only as effective, though, as the receiver's ability to hear them. The din of battle or long distances could make using noise less effective. They were also limited in the amount of information they could convey; the information must be simple, such as attack or retreat.

Visual cues, such as flags or smoke signals required the receiver to have a clear line of sight to the signal, and know when and where to look for them. Intricate warning systems have though always been used such as scouting towers with fires to signal incoming threats - this could occur at the tactical as well as the strategic level. The armies of the 19th century used two flags in combinations that replicated the alphabet. This allowed commanders the ability to send any order they wanted as they needed to, but still relied on line-of-sight. During the Siege of Paris (1870–71) the defending French effectively used carrier pigeons to relay information between tactical units.

Although visual communication flew at the speed of light, it relied on a direct line of sight between the sender and the receiver. Telegraphs helped theater commanders to move large armies about, but one certainly could not count on using immobile telegraph lines on a changing battlefield. At the end of the 19th century the disparate units across any field were instantaneously joined to their commanders by the invention and mass production of the radio. At first the radio could only broadcast tones, so messages were sent via Morse code. The first field radios used by the United States Army saw action in the Spanish–American War (1898) and the Philippine Insurrection (1899–1902). At the same time as radios were deployed the field telephone was developed and made commercially viable. This caused a new signal occupation specialty to be developed: lineman.

...
Wikipedia