XV Corps Heavy Artillery Instruction 24 June 1916
R.A. 21st Division. Herewith amendments to my operation order 7 to French Group.
Box stamp of XV CORPS HEAVY ARTILLERY No T116/44.
M. le Commandant,
Le 6e Groupe M 75.
Orders have been received that gas shells may be used on any day of the bombardment both by day and night. They may therefore be used on any of the objectives in the special schedule on V. W. X & Y days and nights, but must not be used nearer to our own lines than 800 yards.
For Z day an amended special schedule is attached.
Please destroy the schedule for Z day, previously issued.
Brigade Major, H.A. XV Corps.