21st Divisional Artillery Instruction 19 June 1916
XV Corps 1
62 Inf. Bde. 5
63 : : 5
64 : : 5
Div. Art. 2
Div. Eng. 4
178 Tun. Co. R.E. 1
C. Comdt. 1
7th Div. 1
17th Div. 1
34th Div. 1
50th Inf. Bde. 1
Reference 21 Div 0.0. No 55 dated 17/6/17
The attached Appendix “M” (Continued) is forwarded for inclusion with the above quoted O.O.
Please acknowledge receipt.
O.O. No 22 Appendix 2
Copies of paras marked to all brigades.
Infantry should be warned against indiscriminately cutting lines forward in hostile trenches, as they may be of great use in establishing communication. They should only be cut by infantry signallers, and then on the enemy’s side of the point where instrument is tapped in, so that the line may be put through when a further advance takes place.
The lines running parallel in any line in hostile trenches of which use is to be made, must also be cut towards the enemy, but there is no necessity to cut the line to pieces, as they may be of great value later.
Signal Offices in hostile trenches must be strengthened as soon as possible, and steps taken to get the hastily laid cables replaced by properly laid lines. the best opportunity for the latter will probably be the first night.
Signposts must be put up in trenches to assist bearers of messages to find Signal Offices.
Should a move to the rear be made from any position to which cables have been run, it is essential that the cables be destroyed and not left laid through enemy lines.
In order that a system of Visual Signalling may be successfully carried out. It is essential that messages be limited to those of absolute necessity and be kept as short as possible, usually not more than six words.
A good rule is that only messages equivalent to “Priority” should be sent by Visual.
SITES FOR STATIONS.
Sites for Sending Stations in our front line have been determined by the Divisions concerned, but it will be necessary, as the troops move forward, to select points in the enemy’s lines from which it will be possible to communicate back to Receiving Stations. These should be pointed out to signallers of assaulting infantry, who should know how to recognise the direction of the Receiving Station from the front.
Signallers will, to a large extent, have to depend on their own initiative in selecting suitable positions in enemy’s lines, from which they can use Visual, but a great deal can be done beforehand in instructing them as to the most likely point and the most suitable instrument to use, according to the background. Disc, Lamp and Helio will probably be the most suitable means of sending. The value of a large flag used behind a house or under a bank should not be lost sight of.
A certain number of French lamps are being allotted to each Division to supplement the ordinary Lamp, Electric, Field Signalling.
SIGNALLING TO THE KITE BALLOON.
To gain the attention of the Balloon, the light must be aligned on the basket and not on the Balloon.
At night a signalling lamp will be used in the Balloon, and the signal “R.D.” (“Received”) or “I.M.I.” (“Repeat”) will be used.
If more than one station calls up the Balloon simultaneously at night, the Balloon will send “M.Q”, preceded by the call letter, to the stations which it does not want to read. As soon as it has received the message from one station, it will call up one of the other stations by its station call, followed by the letter “G”, that station will then send its message.
Two Wireless Sets will be allotted to each Division.
The range of these Sets varies from 2,000 to 4,000 yards, according to the aerial it is possible to erect.
The 7th and 21st Divisions will have one Set with each Brigade in the line, which should go forward with Brigade H.Q. when it advances, and be set up in enemy’s lines.
The risk of important information being given to the enemy is so great that restrictions as to the use of wireless are essential. No message is to be sent by wireless without the express sanction of the Headquarters or Officer concerned, who is responsible for every message sent.
When it is necessary to detach a Wireless Station from its normal Headquarters, it will be necessary to detail an Officer, (not a Signal Officer) to be responsible for the messages sent by that station.
REGISTERED ADDRESSES AND TELEGRAPH CODE CALLS.
The amended list of Registered Addresses and Code Calls issued under G.307 dated 16/6/16, will be used on all occasions during operations when a code call or name is necessary, e.g. messages sent forward by telephone lines, visual, aeroplane, balloon, wireless, or pigeon. The code call will be used as station call and the registered address to denote a unit in “address to”, “text”, or “address from” of a message. These registered addresses will not be used in messages transmitted above Corps Headquarters. Corps and Divisional Signal Offices will be responsible for decoding messages for transmission beyond the Corps.