21st Divisional Artillery Instruction 23 June 1916
Ack BM 5
62 Inf Bde
63 “ “
64 “ “
50 Inf Bde.
F. Coy R.E.
Orders have been received for the Division to be prepared to carry out the gas attack on the night U/V (24/25th June).
You will be informed by wire (Message “A”) shortly after 5 p.m. 24th June (and on each subsequent day as necessary) whether all preparations are to be made for the attack.
If preparations are ordered to proceed, definite orders will be received at a later hour from Div. H.Q. (Message “B”) as to whether gas is or is not to be discharged. This order (message “B”) will reach you in time to give very nearly two hours notice of the hour fixed as Zero for the gas attack.
The following order is issued for guidance:-
“It must be distinctly understood that when orders have been issued from Corps H.Q. for the gas attack to proceed, the officers of F. Coy. R.E. are responsible for deciding on the spot, from which emplacements it is not safe to discharge gas, and for suspending or delaying the discharge of gas in any part of the line where danger to our own men might result therefrom.”
Attention is drawn to Appendix “F”. Stokes Mortars will not take part.
It is impossible to say at what hour the warning telegram will be sent.
Messages from Division to Units concerned will be sent “Priority.”
62 Inf Bde must take steps to warn parties of other Brigades who may be working or carrying in the trenches.
Careful arrangements for the use of Vermoral Sprayers (if necessary) must be made.
Message “A” will consist of the words “ROGER” AAA Acknowledge.
Message “”B” will consist of “ROGER” 11 p.m. (or whatever time is ordered) AAA Acknowledge.
11 p.m. (or whatever time is ordered) in Message “B” will be the Zero time for the first discharge.