I. To break down obstacles which are impassable for Infantry, but in doing so to create as few new obstacles in the way of shell craters as possible. To bombard strong points.
II. To isolate from the rear the enemy's batteries and front systems, so that he cannot bring up ammunition or replace guns and cannot bring up food or stores without suffering serious loss. To keep him short of food. To reduce his morale.
III. To teach the enemy to lie at the bottom of his shell holes or dugouts whenever any barrages are going on. After one barrage has passed over him he must always expect others. In doing this, cause as many casualties as possible to reduce his morale. This will be effected by working a succession of dense creeping barrages of every available nature of gun and howitzer over the whole area to a depth of 2000 yards beyond the last objective.
IV. To carry out observed destructive shoots on hostile batteries from now on. As soon as batteries are isolated vide II above, to begin intense C.B. work.
V. The attack will be made behind 5 barrages which will cover a depth of about 1000 yards.
VI. Immediately prior to and during the attack all known hostile battery positions will be neutralised.
VII. Barrages to a depth of about 800 yards will be prepared beforehand which can be put down when the enemy counter attacks, and arrangements will be made for all or any portions of these barrages to creep forward so as to embrace the whole of the enemy reserves.
Table A shows the amount of Artillery which is considered necessary.
The number of 12", 9.2" and 8" Howitzers is calculated to deal with 440 hostile gun pits + a 25% increase making 550 in all (inclusive of the IX Corps front) on the basis of a 7 day bombardment.
6" Howitzers are required in addition for neutralization of some 40 battery positions.
The heavy artillery barrage and bombardment guns are calculated on a scale of:
60 pdr. :1 gun to 60 yards
For back communication in addition:
60 pdr.: 1 gun to 166 yards
If sufficient 60-prs. are not available 6" Hows. might be substituted gun for gun or 18-prs. in proportion of 2 18-prs. to 1 60-pr.
If sufficient 8" or 9.2" are not available substitute 6" How.
= = = =
Additions of 14 September 1917
5. From now on the hostile batteries will be systematically destroyed by observed fire from the air or ground.
6. For 7 days prior to the attack intense counter-battery work and isolating fire will be carried on. Every means of observation should be used to its utmost capacity and concentration shoots should be carried out when means of observation are not available.
7. The hostile batteries will be neutralized with gas shell (if weather conditions are suitable for their employment) for the four hours immediately preceding zero hour on the day of attack. If weather conditions are not suitable for use of gas shell, H.E. or shrapnel will be substituted.
The hostile batteries will be neutralized with gas shell (if the weather permits) in a similar manner from 2 a.m. to 6 a.m. on C Day, i.e., for the four hours immediately preceding the second preparatory barrage on the whole Army front. H.E. or shrapnel will be substituted if weather conditions are unsuitable for gas shell.
During the preparatory barrage which starts at 6 a.m. on C Day the enemy batteries will be neutralized to the same extent as they will be from zero hour on the day of attack.
8. Preparatory barrages and any necessary bombardment will be carried out during the five days preceding the attack.
9. Isolating fire will be carried out by day and night throughout the whole period. The approaches to the front systems and the hostile batteries will be closed by two tiers of fire.
The field artillery and machine guns will deal with the area up to a range of 6,000 yards from their battery positions, the 60-pdrs. and 6-inch guns supplemented if necessary by some 6-inch howitzers will keep all approaches beyond the hostile batteries under fire. As a rule the ammunition allotted for isolating fire will be expended two-thirds by night and one-third by day, but when the weather is such that the air service cannot keep the approaches under observation the amount fired by day must be increased. Arrangements will be made by Second Army for crossing the fire of adjacent corps on such back approaches as can be enfiladed by this means.
10. On the first day of bombardment communication trenches will be blocked by knocking in a length of about 10 yards; places which are under observation from O.P.s should be selected for this purpose when possible.
11. Wire which is known to exist will be cut early in the bombardment.
12. Known machine-gun emplacements and strong points will be bombarded by the heavy artillery using delay action fuses.
13. Telephone exchanges will be destroyed.
14. The morale of the enemy will be reduced by frequently passing a succession of barrages over his shell hole system and dug-outs instead of by the bombardment of trenches. For method of using these barrages see Appendix II attached. [not reproduced]
15. All known hostile O.P.s should be destroyed not later than two days before the day of attack.
16. Gas shell should be used against the hostile battery positions and on shell holes, dug-outs and localities which are believed to be occupied when atmospheric conditions are favourable. They should also sometimes be used in the last portion of a barrage. Gas shell should always be preceded by H.E., the proportion of gas shell being gradually increased.
17. The infantry will advance under an 18-pdr. barrage which will be preceded by at least 4 other barrages on the principles indicated in Appendix I attached. [not reproduced] If considered desirable the 18-pdr. and 4.5-inch howitzer barrage (B) and the machine-gun barrage (C) can be combined and readjusted to form 2 mixed barrages in lieu of the method shown. If greater depth is required the several barrages may be as much as 300 yards apart instead of 200 yards. From the moment the attack commences every battery position believed to be occupied will be neutralized. As many planes as are available and can be employed without jamming should be used for sending down zone calls throughout the day.
18. The rate of fire of 18-pdr. guns for the first two minutes will be increased to four rounds per gun per minute: during the pauses in the advance it will be one round per gun per minute. The barrages will be thickened by smoke shell if necessary.
19. In cases where high ground within 2,000 yards of the objective has considerable command over the ground that the creeping barrages will traverse such as the Zandvoorde Ridge, it may be necessary to keep this high ground under fire, withdrawing the necessary guns from the barrages.
20. The field artillery should be so allotted to barrages that about one-third can be withdrawn at any moment without making a gap in the barrage, to deal with LL and G.F. calls and fleeting opportunities. The same system should be adopted in the heavy artillery with 60-pdr. guns and 6-inch howitzers.
21. Protective barrages in depth should be prepared beforehand. In addition to a barrage along the whole front, more concentrated barrages should be arranged to be put down on certain areas over which a counter-attack may be expected.
22. The proportion in which fuse No. 106 will be supplied is 50 per cent. of No. 106 and 50 per cent. delay for all 6-inch howitzers, 8-inch howitzers and 9.2-inch howitzers. As few No. 106 as possible should be used for C.B. work and in bombardment in order that as many as possible may be available for barrages. 23. With the 18-pdr. 50 per cent. of the ammunition will be H.E., the fuses for which will be 25 per cent. with delay and 75 per cent. without delay.
24. Field artillery and infantry A senior officer of the field artillery supporting it should live with the headquarters of each attacking infantry brigade. Field artillery liaison officers should also be attached to headquarters of each assaulting battalion. Heavy artillery and division commanders
A heavy artillery officer not below the rank of major from the Bombardment Group which is covering the divisional front should live at divisional headquarters with a direct telephone line to the Bombardment Group and through this Group to the Counter-Battery Office.
Heavy artillery with R.F.C.
A senior officer of the heavy artillery should live with the corps R.F.C. squadron.
25. Very careful arrangements must be made to give the personnel of batteries sufficient rest throughout the operations.
26. The protection of ammunition from weather is most important.
[signed] C. H. Harington,