Shoots vs Counter Battery Patrols/Artillery Patrols
Greg spent much of his time on two of the cornerstone activities of the corps squadrons such as 42 Squadron, namely counter battery patrols (otherwise known as artillery patrols, covered here) and the observation of artillery fire – otherwise referred to as artillery observation, artillery registration, or more colloquially a shoot.
If counter battery patrols and their associated zone calls are essentially about target acquisition for the artillery, then the observation of artillery fire – a shoot – is about target degradation and ideally destruction. In a shoot, the aircraft was again the artillery’s ‘eye in the sky’, this time to direct fire onto a target. This was done by air-to-ground radio signals from the aircraft to the artillery unit.
The observation of the artillery fire was, by this stage of the war, generally done by the Pilot of the aircraft. When artillery literature refers to the ‘observer’, it means whoever is making the observation, typically the Pilot. The Observer properly so-called – the chap in the gunner’s compartment of the aircraft – is primarily responsible for the defence of the aircraft, including keeping a lookout for enemy aircraft.
Siege Batteries and Clock Codes
The corps squadrons of the Royal Air Force, and the Royal Flying Corps before them, worked with siege batteries of the Royal Garrison Artillery. Each battery might comprise four artillery pieces, for example 6″ or 8″ howitzers. The aircraft directed the battery’s fire using ‘clock code’ radio signals in which the centre of an imaginary clock face was superimposed on the target. A number from 1 to 12 indicates the direction of a shell’s point of impact from the target, with 12, 3, 6 and 9 representing north, east south and west respectively. A letter code precedes the number to indicate how far away the shell landed. The following diagram illustrates the numbers and letters:
A small complication was that the letter O was used instead of the number 12, in order to shorten messages.
The distance codes were:
OK - Direct hit Y - 10 yards Z - 25 yards A - 50 yards B - 100 yards C - 200 yards D - 300 yards E - 400 yards F - 500 yards
And if the observer in the air couldn’t see where the shell landed, the code sent was:
W - unobserved (wash-out)
So a near ideal sequence of signals for successive shells from a particular gun might be (in Morse code):
C3 - shell landed 200 yards to the east of the target A9 - shell landed 50 yards to the west OK - direct hit.
Figures of Eight
When observing the fire and sending the signals, the aircraft would flying figure-of-eight patterns, as suggested in the SS 131 booklet “Co-operation of Aircraft with Artillery”, Revised Edition, as issued by the General Staff in December 1917:
Ground-to-Air Signalling: Ground Strips
Since wireless transmission only operated from air-to-ground, how did the ground wireless operator communicate back to the aircraft? Various methods were tried during the course of the war. Signalling lamps were not an enduring success, not least because of the need for the pilot to be actually looking in the direction of the lamp at the moment of signalling, which was not always feasible.
A better solution proved to be the more primitive sounding strips of cloth put out on the ground: ground strips. These were typically 12 ft x 1 ft (3.7 m x 0.3 m) strips of white cloth, which could be arranged into pre-designated code symbols or letters. Here is an indication of how the ground strips looked from the air. These examples, taken from The Illustrated London News of 23 January 1915 p107, were stated to be “merely typical signals, and do not represent any actually in use” – just in case it should fall into the wrong hands – but some of them were in fact precisely what was used in 1918:
¦ Direction of Target L Observe for line X Observe for range Z Observe for fuze V Observe for effect of fire N Repeat last signal T Land F Fresh target (additional letters are used with this signal)
And if there was snow on the ground, then dark coloured strips were used instead.
The actual signals used at least from the end of 1917 are given in the ‘Co-operation of Aircraft with Artillery‘ booklet [SS 131] at page 24:
An Example of a Shoot – KD90
This example shows how a pre-arranged shoot might have worked in practice. It is based on Example I of the ‘Co-operation of Aircraft with Artillery‘ booklet [SS 131], adapted with timing details from an actual shoot. That was a shoot on a hostile battery designated as KD90 that was observed by Greg on 1 July 1918 – actually Greg’s first shoot. (For an explanation of how a hostile battery gets a ‘zone’ designation such as KD90 see here.)
The shoot on KD90 was reported in Greg’s Log Book and Diary as well as in 42 Squadron’s Record Book for 1 July 1918. The points of impact of the individual shells and the mean points of impact of the salvos are as written in the example. A summary of Greg’s actual results – which co-incidentally involved a direct hit on No 3 pit, as Example I did – are in the Squadron Record Book. (Actually the Example I direct hit on No 3 pit was while ranging on No 2 pit. But a direct hit is a direct hit!)
In the actual working of this example, all signals from the aircraft would have a prefix. This was made up of the squadron’s call letter (which might be A), the aerial observer’s wireless number (Greg’s was known from this post to be 48), and the battery’s call (which might be R). So all signals from the aircraft would in that case be prefixed A48R. This would be abbreviated to AR after a few exchanges (normally when the first round is fired, according to [SS 131] at page 50).
Prearranged Shoot on Hostile Battery at KD90 for Destruction
145 Siege Battery, Royal Garrison Artillery (8″ Howitzers)
Shoot observed by Lt Gregory (Pilot)
The "ranging point" - the initial target - is the gun at the No. 2 emplacement (or "pit") of the hostile battery. References to No.1 firing, No 2 firing etc. are to the British howitzers. References to No. 1 pit, No. 2 pit etc. are to the enemy gun emplacements.| Time | Signal (Air to Ground) | Ground strip (Ground to Air) | Remarks |
|---|---|---|---|
| 2:20pm | B | Are you receiving my signals? [This was the 'call up'. Repeated until answered.] | |
| 2:25pm | K | Yes | |
| T | Ground strip K acknowledged | ||
| A KD90 | Stand by for shoot on KD90 | ||
| F | Message received | ||
| 2:37pm | L | Battery ready to fire | |
| T | Ground strip L acknowledged | ||
| 2:43pm | G | Fire. [Battery fires two salvos in quick succession to cause casualties among personnel.] | |
| MB9 MC4 | The mean point of impact of the first salvo was at clock code position B9. The mean point of impact of the second was at C4. [These mean points of impact are abbreviated MPIs.] | ||
| G | Fire. [No 1. fires] | ||
| A2 G | Point of impact of No. 1 was A2. Fire. [No 2. fires] | ||
| Z8 G | Point of impact of No. 2 was Z8. Fire. [No 3. fires] | ||
| Y2 G | Point of impact of No. 3 was Y2. Fire. [No 4. fires] | ||
| Z6 OK3 G | Point of impact of No. 4 was Z6 in relation to No. 2 pit (the ranging point) but OK (a direct hit) on No. 3 pit. Fire. [No 1. fires] | ||
| OK G | Point of impact of No. 1 was OK (a direct hit) in relation to No. 2 pit (the ranging point). Fire. [No 2. fires] | ||
| ...and so on, until the Battery Commander is satisfied that each gun is ranged. He then puts out the ground strip... | |||
| 4:00pm | V | Observe for fire for effect. [The guns all now fire "for real" at No. 2 pit.] | |
| MOK | Aircraft sends occasional MPI signals, such this one: The mean point of impact of the last salvo was OK, a direct hit. | ||
| SW Z6 | When sufficient effect has been obtained on No. 2 pit, the aircraft sends Switch and the clock code for the No. 3 pit in relation to the No. 2 pit (here Z6). The guns now fire for effect on No. 3 pit. | ||
| SW Z6 | Now switch to No. 4 pit, at clock code Z6 in relation to No. 3 pit. The guns now fire for effect on No. 4 pit. | ||
| SW AO | Now switch to No. 1 pit, at clock code AO in relation to No. 4 pit. Recall that O means 12 o'clock. The guns now fire for effect on No. 1 pit. | ||
| When the Battery Commander is satisfied that the aircraft's task is finished, he puts out... | |||
| 5:05pm | T | Go home. |
G to V Time
One thing that everyone paid close attention to was the G to V time. This was the time between the aircraft first signalling ‘Fire’, and the battery putting out the ground signal ‘Observe for fire for effect’. This interval indicated how long it took for the battery commander to be satisfied that his guns were properly ranged on the target. Because of the importance of this metric, the Squadron Record Book included it in the official report of the shoot. Obviously, the shorter it was, the better. On this occasion, it was 1 hour and 17 minutes.
Squadron Record Book Entry
Here’s how the Squadron Record Book recorded the shoot. It’s the first entry on the (hard to read) page. Transcript (and translation) below.
Type and Number: R.E.8.27
Pilot and Observer: P. Lt Gregory. O. Lt Watkins.
Duty: Art Obs 145 S.B. (8" How) on K.D.90.
Hour of Start: 2.10pm
Hour of Return: 5.15pm
Remarks:
SUCCESSFUL. Called up 2.20pm. K. 2.25pm. L. 2.37pm. G. 2.43pm. V. 4.0pm. G. to V. 1-17mins
OBSERVED:- 1 O.K. 1 Y. 2 Z. 8 A. 16 B. 6 C. 2 D. 7 W. 42 ranging rounds. "V" out and 3 M.O.K. sent.
Direct hit on No. 3 Pit. T. out 5.5pm.
Shoot by P. Height 6000'.
MISC INF. 2.50p O.K. on house at K.36.d.0.7.
4.25pm and 4.55pm called C.W.S. X. out. A.A. very active in back areas. No movement seen North of CANAL. No trains. Obs. fired 600 rounds into NEUF BERQUIN, MERVILLE STATION and EPINETTE. Pilot fired 100 rounds into MERVILLE STATION. Vis. good at first, poor later. Obs. by P. & O.
Translation of Remarks:
Remarks: SUCCESSFUL.
Called up [B: Are you receiving my signal?] 2.20pm.
K. [Yes] 2.25pm.
L. [Battery ready to fire] 2.37pm.
G. [First 'Fire' command] 2.43pm.
V. [Observe for fire for effect; ie Battery Commander is satisfied that guns are now ranged, and will now fire 'for real' - please observe] 4.0pm.
G. to V. [Time taken to range battery] 1-17mins
OBSERVED:- 1 O.K. [Direct hit]
1 Y. [Within 10 yards]
2 Z. [Within 25 yards]
8 A. [Within 50 yards]
16 B. [Within 100 yards]
6 C. [Within 200 yards]
2 D. [Within 300 yards]
7 W. [Washout - unobserved]
42 ranging rounds.
"V" out and 3 M.O.K. [3 Mean-point-of-impact (of salvos) are direct hits] sent.
Direct hit on No. 3 Pit.
T. out [Battery telling aircraft to go home] 5.5pm.
Shoot by P. [Pilot did the observing of the shoot; the Observer would have been fully occupied watching for enemy aircraft] Height 6000'.
MISC INF. 2.50p O.K. [direct hit] on house at K.36.d.0.7. [Map reference of house just next to hostile battery at KD90]
4.25pm and 4.55pm called C.W.S. [The Central Wireless Station of the squadron] X. out. [Change target] A.A. very active in back areas. No movement seen North of CANAL. No trains. Obs. fired 600 rounds into NEUF BERQUIN, MERVILLE STATION and EPINETTE. Pilot fired 100 rounds into MERVILLE STATION. Vis. good at first, poor later. Obs. by P. & O. [Pilot and Observer both contributed to miscellaneous info.]
Header image: BL 8” Mk VI Howitzer operated by 54th Australian Siege Battery near Ypres on 15 September 1917. Public domain work.