CAB80-8 — Page 191

(b). The accepted scales were as follows :-

London area.

Elsewhere.

4.5" 4,000

2,500

3.7"

40 m.m.

3,000

1,500

2,000

1,500

163

This is

The above figures for 3.7" were a reduction on previous estimates. This reduction was considered to be reasonable owing to the large increases in the number of guns. clearly a saund principle having regard to the increased destructive and deterrent effect of increasing the scale of defence for a given objective.

The figures were based on the assumption of about 55,000 raids being directed against these islands in the six months under review, of which the guns were supposed to engage about 35,000 i.e. about 1,300 per week.

(c). It was considered that the bulk of the enemy air effort

would be directed against Great Britain. Experience suggests that this may not be so, and that hostile air forces may be used mainly in support of their armies. A given sized air force cannot however attack the two objectives with the same intensity, hance a large scale air effort on the continent implies a corresponding dimunition of effort on Great Britain, and vice versa.

(ii). B.E.F.

(a). The scale of expenditure is assessed at present at 30 RF.G.

per day regardless of whether the guns are in the forward or back areas,

The ammunition expenditure in France in 1918 merits consideration. Between January 1st and October 31st 1918, about 1,000,000 rounds were fired by an average of 300 guns. This corresponds to a daily rate of about 11 R.P.G.

It should be noted that about 95% of this expenditure was in the forward areas, where the bulk of targets were single aircraft.

An estimate of the number of targets engaged shows an average of 1,000 per week, i.e. about 25,000 for six months.

This figure should be viewed in relation to that on which the A.D.G.B. figures for the first six months of war have been based. (i.e. 1,300 per week and 35,000 per six months).

Although a much higher proportion of attacks may now be expected on back areas, these attacks will in a large measure be carried out in force and thus not add markedly to the total numbers. The incidence of reconnaissance and artillery aircraft in the forward areas is hardly likely substantially to exceed that of 1918.

(b).

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Certain new factors have arisen/...

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