XV Corps Instruction 17 June 1916
USE OF LACHRYMATORY AND GAS SHELLS
U to Z Days
Reference 15/CA/10/23 and 10/32 of 12th and 14th instants.
1. Lachrymatory and Gas shells can be most usefully employed for counter-battery work, interrupting communications, especially blocking communication trenches, and against billets, woods, villages and hollows.
2. The effect of the shells is very local, and a large number are required in one place to be of any real use.
3. 4.5” Howitzers.
(a) The bulk of the rounds should be kept for Z day, but there is no objection to a small proportion being used for special objects on the other days.
(b) The 4.5” Howitzers belonging to Divisional Artilleries and the Battery attached to the Heavy Artillery can fire –
on U to Y days, 800 yards from our line in any wind:
300 yards if the wind is blowing from our lines.,
on Z day, the same as regards distances and wind, but not later than 30 minutes before Zero on ground short of the final objective.
(c) The battery attached to the Heavy Artillery should use these shells chiefly for counter-battery work and to a less extent for barraging distant points.
4. The French 77 mm should be used freely on all days:-
On U to Y days, under same conditions of wind as for 4.5” Howitzers.
On Z day, beyond the final objective. As the Infantry advance near to this, the distance beyond the final objective must be increased.
5. A third of these shells for the 4.5” Howitzers should be retained for further operations.
Brigadier General., R.A., XV Corps
17th June 1916.
R.A. forwarded AP