The lines of connection between the infantry and the artillery must be separate from those within the infantry area and those between the artillery commander and his subordinate units.
Confidential information should never be telephoned except in cipher. Conventional designations are employed to call the different posts. Strict regulations are maintained as to who should use the telephone and for what purposes.
The weak point of a telephone system is that it is often broken by bombardment or earth-slides. This can be partially remedied by constructing as few direct lines as possible, by burying the wires in the bottom of the boyaux, and by executing repairs as quickly as possible.
(b) Wireless and Ground Telegraphy: The battalions in the first line have ground telegraph apparatus connecting them with the regimental headquarters, and these, in turn, can communicate with the general headquarters by wireless. This means of communication is only employed when the telephone cannot be used.
(c) Signalling: It is difficult to establish signal communication within the sector without being seen by the enemy. However, at night with flashlights it is possible, especially in hilly country, to communicate from front to rear within the position. The receiving post should be able to certify received messages. When practicable, communications should be established between the command post of the center of resistance and the sector command posts, and from the latter post to the artillery. This method of liaison is organized as a duplicating means or as a temporary substitute for the telephone.
(d) Rockets: Signal rockets are used to communicate with the rear. Different forms and colors of rockets are used to signify different things. As we have seen, the most important use of the rocket is to signal for barrage fire. It is often necessary to relay a rocket signal from a second position in the rear to make absolutely sure that it reaches the artillery support.
Signal rockets are also used to communicate with aëroplanes, but this means is usually only employed during an attack.
(e) Runners: The liaison established with runners is best of all, from the point of view that it usually never fails. During heavy shelling it is the only sure means of communication.
The ordinary messengers or orderlies are not used as runners. A chain of trained runners is used, located in a little post, shelters, or shell holes; Each post contains three runners, their distance being from 150 to 300 yards apart. Each runner is selected from the unit located near the next post in the chain, that is, the one to which he is to run. Often the divisional cavalry furnish these runners.