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(b) To establish Heavy Artillery to deny orts and
landings to the enemy and to support the counter attacks which would be launched against any attempted bridge-head.
Of the equipments detailed in paragraph 1, the 9.2-inch railway guns along could be made available to support counter- attacks, but they would have to be withdrawn from their present coast defence role to do so.
3.
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The role of the "Very Long Range Group", except for the 16-inch guns, is primarily bombardment of targets on the French coast. They may also be able to engaged ships, but this would be limited to "running past line" fire, owing to their limited and slow rate of traverse.
The "Long Range Group" and the 16-inch guns will be employed to deny the Straits of Dover to enemy shipping, in a counter-invasion role, or against other sea-borne enemy action.
It is pointed out, however, that the 9.2-inch railway guns were not designed as Coast Artillery equipments and are not provided with coast artillery fire control instruments, and therefore they can only engage ships by improvised methods.
4.
To carry out their role, both these "very long" and "long range" groups must be capable of engaging targets at ranges at which accurate observation from the Battery Observation Posts is impossible under conditions of normal visibility. Some means of carrying out the necessary reconnaissance, locating targets and observing fall of shot is therefore necessary.
5.
As far as the engagement of land targets is concerned, the only means of carrying out the above tasks is by air co-operation.
6.
With regard to anti-ship firing, there are two possibilities:-
a) By R.D.F. methods.
By air co-operation.
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Until August, 1941, the greatest accuracy which can be expected from R.D.F. sets will be in the order of + or 400 yards range and + or 1 bearing up to about 30,000 yards. Thereafter, further sets which are expected to produce an 10 bearing, accuracy of + or 50 yards range and + or should be available.
ships.
7.
M
g
Both types of sets will be capable only of detecting
They will not record actual fall of shot.
It is considered that the value to be obtained from the guns specially emplaced to deny the Straits to enemy shipping is almost negligible unless observation of fall of shot is possible. Further developments in R.D.F. after August, 1941, envisage sets which will also record actual fall of shot,
but thereby enabling fire to be corrected on to the target; for many months to come the only possible means of obtaining these observations at long ranges will be by air co-operation.
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