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INTRODUCTION

Originally, in World War 1, artillery intelligence meant all the activities to obtain and process information about hostile artillery.  Later its use narrowed to the specialist intelligence processes, and locating became the term for the technical methods used by specialist artillery, such as flash spotting and radars, for finding the position of hostile batteries.  This page uses the broader meaning.  Counter-battery refers to the organisation and actions to attack hostile artillery that has been found by whatever means.  Counter-mortar became important in World War 2 but after that war it was merged with counter-battery to become counter-bombardment.  Subsequently NATO adopted the term ‘counterbattery fire’ currently defined as “Fire delivered for the purpose of destroying or neutralizing the enemy's fire support system.”

ORIGINS

In the direct fire era artillery intelligence was non-existent because the enemy’s guns were as visible as any other target and it didn’t need any specialist counter-battery activity.  In Field Artillery Training (FAT), 1906, enemy batteries were expected to be ranged if possible and attacked with rapid fire. Searching fire (at that time fire aimed up to 400 yards beyond the ranged point in 100 yard increments) could be used and was to be if the enemy had only been located by their gun flashes.  Graze fuzes  were recommended because they would penetrate gun shields.  There does not seem to have been any idea of ‘scouting for guns’ nor any other kind of organised artillery intelligence activity.  FAT 1912, made no mention of counter-battery, although it did note that the ‘principal duty’ of heavy artillery was ‘to engage shielded artillery with oblique fire’. It made no mention of specific information gathering or reconnaissance against enemy artillery.

However,  a seminal event had occurred 6-7 May 1900 at Fourteen Streams in South Africa.  Captain BA Warry of the Essex Regiment in a balloon of 3 Balloon Section RE controlled a 6-inch gun newly delivered to 20 Bde RFA and mounted on a railwagon against Boer artillery that could not be seen from British positions on the ground.  After relatively short engagements on two successive days the three Boer guns were silenced.  It was counter-battery indirect fire controlled by an air observer.  This little known and recognised event was an augury of things to come.

Nevertheless Bethel, 1911 only used ‘counter-battery’ with regards to the French tactic of having counter-batteries, with one coming into action when a hostile battery is found and conducting a one-on-one engagement.  His discussion on ‘Artillery versus Artillery’ focused on the application of fire, shrapnel to give about 75% graze bursts, but oblique fire, ie into the flank of the enemy, used whenever possible.  He also stated: “It must be remembered that killing the detachment will not permanently silence good artillery, since casualties will be replaced by men from the wagon lines and ammunition column, down to the last driver.  Other troops may be demoralized after suffering 25% casualties, but there is no record of a gunner running away from his gun.”  He recommended the use of kite balloons for observation against batteries behind a crest but otherwise searching fire or cross (oblique) fire.  He also stated that massed fire by several dispersed batteries on each hostile battery in turn would be more effective than one-on-one engagements. In FAT 1914 indirect fire was expected to mean deploying guns behind a crest close to the front.  The counter-battery fire solution to this was to range the crest then use shrapnel with ‘searching’ fire up to 400 yards beyond. 

Air observation was practised although air-ground communications were problematic and for this reason tethered spherical balloons (or kites in rough weather), which had telephone lines, had advantages.  However, they had to be a some distance behind the front which limited their observation compared to an aeroplane.  Balloons and kites were used for observation in live firing practices by both field and garrison artillery.

In the 1910 manouvres on Salisbury Plain three artillery officers flew their privately owned aircraft on reconnaissance flights, they weren't often called on and bad weather delayed many flights, the results were less than impressive.   However, an airship, Beta, of the Air Battalion RE also flew, covering some 1000 miles and sent many reconnaissance reports.  There were also some experiments with wireless from another aircraft.  The Royal Flying Corps, with Naval and Military Wings, was formed in 1912, aeroplanes and airships were successfully used for reconnaissance in that year's manouvres, the latter making good use of their wireless.  However, it also became clear to astute officers that air observation was a skilled task and not something that could be instantly mastered - an RFC lecturer at staff college stating that "an untrained observer was a useless encumbrance".   However, co-ordination to position the pilot to observe artillery fall of shot was tricky and 3 Sqn RFC was specifically tasked to develop air observation procedures with artillery.  From this instructions for co-operation between aircraft and artillery were developed for target acquisition and observation of fire.  They were published in both RFA and RFC pamphlets in 1914, although it seems that they were not the final word and continued to evolve.  Another consequence was practising concealment and putting the guns into field emplacements (ie ‘digging-in’) during training.  In 1913 all airships and balloons were handed to the Naval Wing although kites remained with the Military Wing.

In the 1890's the Garrison Artillery siege batteries had developed ‘instrumental observation’, in essence cross observation with special instruments, to accurately correct their own fire.  This required either sight of the enemy guns or the smoke from their firing.  However, the introduction of cordite type propellant that was essentially smokeless, although it did provide a flash, created a problem.  Nevertheless, by 1905 ways had been found to produce gun flashes on firing ranges to practice instrumental observation and fire at the flashes.  By the end of the decade the older specialised instruments were partially replaced with standard ones, notably the No 2 Director, that were a lot lighter.  By this time the mobilisation strength of the siege artillery was six batteries of 6-inch howitzers.  The heavy artillery comprised a divisional heavy battery with 4 × 60-pr Guns, although the Territorial Force batteries had 4.7-inch Guns.

Unlike UK, France and Germany had created some counter-battery capability before WW1.  Germany had created an information service that seems to have included artillery intelligence, a German officer had patented a method of sound ranging, they had flash spotting units for siege operations and were using aerial photography.  The French had done some work on sound ranging and had a flash spotting capability as well as using air photography.  During the Italo-Turkish War 1911-12 in Libya the Italians had used aerial photography. 

WORLD WAR 1 - 1914

A little later a British heavy (60-pr) battery engaged German 15 and 21 cm Howitzer batteries for the first time.  The 15 cm battery was silenced but the 60-pr battery was forced to move.  The Germans too had their successes, including with air observation of 21 cm Howitzer fire against a 60-pr battery.  The first British siege batteries arrived towards the end of September, albeit equipped with the aging 6-inch 30 cwt howitzers.  Trenches also started to be dug and artillery started deploying further back, although lack of suitable communications was a problem.  Dummy and alternate gun positions started being used to avoid German aerial observation and counter-battery fire.

However, there were only a few aircraft with a wireless, a single flight in No 4 Squadron RFC, these wireless telegraphy sets were only air to ground, they were also very bulky and being 'telegraphy' meant they only transmitted using Morse-code.  Their task was to locate hostile batteries (HB) and report to the divisional Commanders Royal Artillery (CRA) who were responsible for counter-battery (CB) fire.  Aircraft also had signal lamps and dropped messages, and could ‘mark’ the target by dropping a smoke ball or ‘dipping’ the aircraft over it.  These manoeuvres were observed from the ground by a heavy battery, they used a plane table and its alidade to plot the bearing to the HB.  Combinations of coloured flares were used by the aircrew to signal corrections to the battery in accordance with Co-operation of Aeroplanes with Artillery.  From locating an HB to having effective fire onto it took about 10 minutes, presumably in ideal circumstances.  In November 1^st Ranging Section Royal Engineers (RE) arrived primarily to fix HBs by cross observation when markers were dropped over them by aircraft.  They became the Ranging & Survey section in April 1915 and helped develop flash spotting techniques.

At the beginning of October a siege battery used observation of fire methods for flash spotting.  There was also much unorganised flash spotting during the autumn.  It was mostly inaccurate because there was no survey; observation positions needed to be accurately surveyed for both fixation and orientation.  However, the OP coordinates were not precisely known, their observed bearings were inaccurate and there were no effective procedures for coordinating observations.  Nevertheless, depression range-finding (standard practice in RGA coast artillery) was useful in at least one position. 

By the end of 1914 artillery telephone communications were becoming reliable and aerial observation for heavy and siege batteries, relying on wireless, Morse code and reported observations using the clock code was established.  French gridded maps enabled reasonably effective map shooting at shorter ranges, providing there was no wind and temperature was about standard.  Such conditions could not, of course, be guaranteed at a particular date, time and place.  The effects of non-standard conditions were known, and there was a method to correct for them by changing the ballistic co-efficient, but not a quick and simple procedure.  The problem was providing the necessary data to correct for the variations of the moment from standard meteor conditions. 

Further Notes on Artillery in the Present War November 1914 identified CB as one of the main tasks of artillery, and clearly not envisaged 6 months earlier.  However, CB required target acquisition, and while a ground observer could sometimes see an enemy battery, more usually hostile batteries (HBs) were out of sight.  This had two implications.  First effective means were required to find HBs, and second, the normal gunnery procedure whereby the artillery observer (battery commander or designated observing officer) ordered the bearing and range to the target was no longer possible.  This meant that ‘map shooting’ and calculating firing data at the gun position were required.

WORLD WAR 1 1915

Organisation

A significant step was the formation, on 28 February 1915, of No 1 and No 2 Heavy Artillery Reserve (HAR) Groups commanded by Brigadier-Generals G McK Franks and HCC Uniacke respectively.  These Groups were designated as corps groups although they were each allocated to an army.  Initially they commanded the 8-inch, which entered service that month, and 9.2 -inch Howitzers but took over all 60-pr and 4.7-inch heavy guns within a few months.  However, by the end of 1915 there were still only five Groups, including one GHQ reserve, for the ten corps in France although by then there were also RGA Brigades (ie battalions) assigned to Armies and Corps.  Mid year the Commander in Chief of the BEF sought a new scale of heavy artillery, noting that Germany had reduced their field artillery to 3.5 per 1000 bayonets but increased heavy artillery to 1.7.  He sought a scale of a 6-inch howitzer battery per division (in addition to the 60-pr), two batteries of 8-inch or 9.2-inch howitzer per corps and one battery or 12 or 15 inch howitzers per army.  This amounted to 8 heavy and siege btys per 'standard' corps of three divisions (ignoring the army batteries).

The creation of the HAR Groups relieved the divisional artillery commanders of the responsibility for counter-battery.  However, the corps artillery advisors (Brigadier-Generals, Royal Artillery) lacked executive authority and did not become commanders (General Officer Commanding Royal Artillery) until October (when RGA brigades had to be commanded).  The HAR Groups took on the task of locating HBs as well as engaging them.  Although bombardment to support specific operations was important, CB became the most important and continuous part of their role.  Their commanders provided the driving force to develop the necessary techniques, tactics and procedures.  

The HAR Groups were the only artillery HQ with an intelligence officer as well as control of the most effective CB firepower.  This meant that CB and artillery intelligence was effectively an army level activity.  However, the command level at which CB should be organised and controlled was a contentious issue. 

Extensive German use of enfilade fire meant that HBs were often outside their target division’s front, add to this if opposing divisional boundaries did not coincide then some HBs in an enemy division would always be deployed outside the boundaries of their opposing division.  Corps control was required but, of course, the same issue existed at corps level and at army level.  Some artillery officers thought that CB should be in an independent organisation outside corps control, but such as notion was alien to mainstream artillery thinking that emphasised the need for a close relationship with the infantry, and hence the need for artillery organisation to mirror the normal brigade – division – corps – army arrangements.

The best way to organise and assign responsibility for CB was a discussion that lasted into 1916 and it was not until early 1917 that effective command and control arrangements were formally created.  Line communications also increased in complexity, one to one links evolved into telephone networks with exchanges linking together observers, guns and HQs.

Aerial Reconnaissance

Aerial reconnaissance by aircraft was the main source of information about the location of HBs, and this remained so throughout the war.  In April 1915 the B.E.2c became the standard aircraft for reconnaissance and artillery observation.  It's unclear if RFC kites were used and it seems that the RN's balloons and airships were also absent.  However, in early May 1915 a kite-balloon was borrowed from the French.  This type of balloon designed by a French engineer, Captain Caquot; was a shortened version of a German Drachen type sausage balloon but stabilised by having horizontal and vertical 'fins' at one end.  Its key characteristic was that it provided a stable platform even in high winds, unlike the spherical balloon that became unstable and oscillated in a mild breeze.  Both aircraft and tethered kite-balloons of the RFC also provided information but the former were the main source.  In September four RN kite-balloons reached France.  Later all balloons were transferred to the RFC.

In 1915 when the growing BEF was reorganised into armies, each army had a RFC wing of four squadrons, essentially one per corps, primarily concerned with artillery co-operation.  In 1916 as the RFC expanded each army grew to a RFC brigade with two wings, one providing a squadron to each corps.  Subsequent expansion increased to a wing per corps, including a balloon company, although in 1917 these were concentrated into a balloon wing in each army brigade RFC.  The corps squadron maintained continuous observation over the corps front during daylight (weather permitting).  However, it wasn’t the trenchline frontage, it was the ‘corps counter-battery area’.  This was normally divided into two sub-areas for two of the squadron’s flights, the third flight providing observation for other artillery tasks.  Of course being the British Army it's likely that different corps operated differently and the aerial photographic effort also had to be managed.  Hand-held cameras started being used for aerial photograph in late 1914.  An experimental RFC photographic section was formed in January 1915.   In February the 'A-type' handheld camera designed for airborne use arrived.  By mid-year the C-type appeared, it was designed to be fixed to the aircraft and was simpler to use.  Film processing soon became a capability in the squadrons.

In December 1914 a standard British method for squaring (not gridding) maps was agreed, although it was many months before map coverage of the BEF area was complete.  These maps used 6000 x 6000 yard lettered squares to provide a common frame of reference.  This enabled the introduction of the JJ Call (subsequently Zone Call) by II Corps in April 1915.  Fire by Selected Batteries, issued by GHQ in July 1915, described the standard procedure.  For artillery purposes the large square was divided into 3000 x 3000 yard quarters, called ‘Zones’, and labeled A – D (later alternate large squares used W – Z).  Normally each Zone was the area for at least one battery, the number of batteries assigned to a Zone increased throughout the war, which enabled rostering and or multi-battery concentrations.  Wireless communications were air-to-ground only.  Marker strips at the gun position were used (sparingly) to signal back to the aircraft if required.  This process enabled air observers to report both target locations and their observations of the fall of shot.  Before this reporting locations was difficult because there was no frame of reference apart from vague indications such as 'SW of village (name)', which provided neither brevity nor precision and in effect limited air observation to pre-arranged targets.   The new procedure allowed opportunity targets to be attacked.

Figure 1 – Map Sheet W Divided into Zones A - D

For the Zone Call procedure all assigned batteries and artillery commanders had RFC receiving sets with RFC operators who listened for calls in their Zone.  An example call (transmitted in Morse code) would be “FB NF W21b34 N3” where F was squadron and B aircraft identities, NF (‘now firing’) meant HBs firing, then the map reference (main square W, 21 being in Zone C), b34 meant the North East quarter of square 21, 3/10s (75 yards) to the right from the left side and 4/10s (100 yards) up from the bottom.  N3 being the third target during flight.  The RFC wireless operator with the battery had to be able to pick target calls in his battery’s Zone.  With NF targets the goal was usually neutralisation, not destruction.

The battery could fire at once, but if already engaged only one gun or section was used for ranging.  Once the ranging gun fired the air observer reported where the shell fell relative to the target by using the clock code.  The problem was that this method was time consuming, and the aircraft had to be correctly positioned when the rounds fell so that they could be observed.

Figure 2 – Clock Code

The clockface was centred on the target and aligned with 12 o’clock North.  The air observer reported where the round fell, eg “C3”.  The lettered bands were distances in yards from the centre (target): Y 10, Z 25, A 50, B 100, C 200, D 300, E 400, F 500

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The officer on the battery position and controlling the guns from the Battery Commander’s Post then converted the observation into a correction to the firing data that was ordered to the guns.  The issued device for this was the ‘Artillery dial Range Corrector’, although entrepreneurial officers developed others that were produced by companies in UK.

Figure 3 – Auto dial Range Corrector

Major LA Notcutt MC invented the Artillery dial Range Corrector and was officially adopted for batteries to convert clock code observations into corrections to firing data, his improved version was the Auto Range Corrector.  The observation was marked on the transparent rotating dial, which was set to the line of fire bearing, the correction to range and deflection was then read from the 6 × 9 inch Ivorine base vertically below the plot at the target range.  Produced by JW Steward Ltd it was advertised at £1 5s (over two weeks basic pay for a private soldier).

The first kite balloon, borrowed from the French, was used in May 1915.  It was a response to the lack of OP positions in Ypres salient.  Their ability to detect HBs from a balloon depended on the terrain, hills still masked some ground from even balloon observers.  Balloon observation was almost entirely connected to artillery, in European conditions troop movements could not be seen from any distance unless it was a large body of troops.

Balloons were not very effective in finding accurate locations, but could range guns onto visible targets in forward area and were normally affiliated to a battery for immediate response.  They were also good for collecting intelligence about enemy artillery firing activity, particularly at night.  The advantage that balloons had over aircraft was that the observer had a telephone line to the ground, two way communications, and was connected into the artillery communications network.

In October 2^nd Army, where Major-General G McK Franks was by now GOCRA, recognised they were overly dependent on aerial observation for CB and needed to develop other methods.

Flash-Spotting

By mid-1915 most corps artilleries were doing some flash-spotting, with II Corps perhaps the most successful.  There were two methods, which could be combined:

• Measuring bearings to the flash from different positions, then plotting the bearings to find their intersection; or
• ‘Flash-to-bang time’, measuring the bearing to the flash and using a stopwatch to measure the time from flash to the sound reaching the observer, this time was then converted to a distance (speed of sound ~330 metres/second) and measured on the plotted bearing.  One problem was differentiating the sound of the gun firing from the sound of its shells if they were supersonic, compounded by the fact that the sound of firing could be inaudible to the human ear.

They used alidades to measure bearings, but instead of a full planetable only sectors were needed for plotting the direction to an HB.  Flash-to-bang was found not to be particularly accurate, but was useful as an error check and for identifying which of several known HBs was firing.  Intersection became the normal method but at least three bearings were needed, with observation posts a reasonable distance apart to give an accurate result.  The problem was ensuring that all three observers were looking at the same flashes.

The HAR Groups and RE Ranging & Survey section worked on improving flash-spotting and using bearings from cross-observation, they soon achieved some success with a chain of observers linked by telephone.  In the autumn both 2^nd and 3^rd Armies, where flash-spotting was by corps RA units, decided to reorganise them onto an Army basis to provide continuity when corps moved.  The organisation was either a single group for an army front or sub-sections of at least three posts.

The pre-war Observation of Fire Instruments (accurate to 1 minute) were effective, although their weight was a disadvantage as was their narrow field of view, and their optical quality was somewhat low.  Flash spotting also used a much longer ‘base’, several thousand yards and chart plotting, instead of the 500 yards and slide rule calculation of the RGA’s observation of fire technique described in the Handbook of Artillery Instruments, 1914.  There seems also to have been some use of No 2 Directors, which were probably more widely available.  RE observers in 1^st Army merely reported flashes to artillery, this was not particularly useful.  They also used survey theodolites for observation, these weren’t particularly robust, lacked a wide field of view and good magnification, and had unnecessarily precise angular measurement. 

Figure 4 - Apparatus, Observation of Fire Instrument

The instrument in its box weighed 90 lbs, plus 70 lbs for the tripod.

Flash spotting was most effective at night, because the flash was more pronounced and could be seen some way above the gun muzzle.  When muzzles were in or almost in view their pinpoint flashes could be seen in daylight, particularly when it was overcast.  These flashes gave more accurate results than the bigger night time flashes that were far easier to detect visually.  The day time pinpoints needed meticulous observation through instruments with plenty of magnification, although these tended to have smaller fields of view.

During 1915 the No 5 Director (accurate to 5 minutes). entered service with batteries, and became widely used for flash-spotting, its weight was an improvement on the observation of fire instrument but the optical quality was still poor, although separate observation telescopes offset this.  Being relatively light in weight it had to be firmly mounted.  However, the main inconvenience was that directors were graduated to 180° left and right instead of the full circle required for flash-spotting bearings.

Figure 5 - No 5 Director

Click image to see enlargement

By December 1915 No 2 HAR Group’s intelligence officer had established flash-spotting posts with the Group HQ collating their observations.  However, flash-spotting was hindered by poor maps, lack of accurately surveyed fixation and orientation, and the difficulty of collating observations.  This collation was based on synchronised watches to provide a common time base as the means to know which observations related to which HB.  Times then had to be compared to find ‘matches’ and hence, hopefully, observations of the same HB.  However, despite some success it was generally ineffective unless only very few HBs were active, even when chronometers were used. 

By the end of the year GHQ decided to put all flash-spotting under each army’s Field Survey Section, 1^st and 3^rd Armies had quickly agreed to and implemented this but 2^nd Army was less keen, presumably because 2 HAR Group were managing reasonably well.  They made the change early in 1916. 

Sound Ranging

The French experiments with various methods of sound ranging started soon after the outbreak of war, these included men with stop watches, men signalling (‘tapping’) when sound reached them and microphones, and various recording apparatus.  They were in use from January 1915, including adjacent to the BEF.  GHQ arranged for a British party to visit the developers in Paris and then at the front.  Despite some reservations there was sufficient support for its limited adoption. 

The key components were listening ‘devices’ and a means of recording when a sound wave reached each ‘device’.  The latter seemed the difficult bit, and Lucien Bull’s (a British expatriate in Paris and expert in optics and mechanics) seemed to be best.  This used an Eindhoven five (later 6) string galvanometer and recorded the string vibration for each microphone on to moving photographic film with a time base marked.  The first British sound ranging section, commanded by the Nobel laureate Captain Lawrence Bragg received Bull equipment in October 1915 and joined 2^nd Army.  

Bragg’s first sound ranging base had five telephone type carbon microphones each connected by field cable to Bull’s recording apparatus.  It was thought that a base of about 5500 yards length was needed, but the initial base was only 3000 yards because of expected difficulties in getting the Signal Service to maintain the cables.  The recording apparatus, moving film, was switched on when guns fired.  This required an advanced post listening for HBs firing and reporting to the recording post.  However, this first set could only locate a HB into a 500 yard square.  This was helpful because it could focus air reconnaissance, but not particularly useful because it was far too imprecise for any chance of effective CB fire. 

The first location was made in November and by December there was sufficient confidence in its potential for two sections to be authorised for each of the four armies of the BEF.  These sections, 21 men strong including three officers, were designated Z – R (less U, with Bragg’s original section becoming W).

CB Tactics

There is a paper, drafted in late 1915 by a staff officer for an unidentified GOCRA, Counter Battery Work in Trench Warfare, which sets out the ‘state of the art’ at that time.  It identifies the Principles of Action (noting that they were from various memoranda by General Franks), Intelligence, and Organisation and Control.  Frank’s principles remained for the rest of the war. 

It recognised two categories for CB work: destruction and neutralisation.  Destruction could only be achieved by heavy howitzers, 6-inch and up, in the case of entrenched batteries.  Guns (not Howitzers) could only undertake destruction against artillery protected by light earthworks and their large 50% Zones meant that it was important to select the right battery. The Zone increased with range so effective enfilade fire could be delivered at greater range than fire towards the front of a HB.

Neutralisation was chiefly required in attack and defence to relieve infantry from enemy fire that caused casualties and interfered with their tasks.  Neutralisation could not knock out a large proportion of German artillery before or during action.  The role of neutralisation was to stop or prevent its target HB firing.  The implication being that when neutralisation stopped the enemy would soon resume firing.  However, throughout WW1 neutralisation of HBs generally assumed that there would be some ‘carry-over’ effect after the CB fire stopped.  Divisional field batteries could be used for neutralisation.

Speed of action was the essence of CB, particularly for neutralisation.  The goal was to get fire onto HBs as soon as they started shooting, if not before, to prevent them firing.  Speed of response required assigned zones of fire and observation, HB information kept up to date, good communications between OPs and CB batteries, and rapid passage of information.  CB commanders had to take the initiative within their authority.  Quick action was essential, battery commanders seldom had time to refer to higher authority.  Higher command influenced the CB battle by organisation and occasionally concentrating fire of several batteries for destructive effect. 

Observers had to have lateral communications so that they could use another battery if a target was outside the arc of fire of their own battery.  It was found that artillery communication channels were fairly fast.  By the time a report from an infantry battalion that they were under fire reached HAR Group HQ via divisional HQ the CB fire had already been delivered.

It was also recognised that different types of HB had to be dealt with in priority.  This depended on which HB roles are most likely to affect infantry.  Enemy howitzers were most trouble when own troops were forming for an assault, after an enemy line was captured, and during fire on own trenches.  Enemy field guns caused most loss during the infantry advance.

Heavy howitzers were needed for deliberate destruction of HBs but this needed exact observation, which could usually only come from the RFC.  Guns were effective against HBs that were not entrenched, including with heavy guns firing shrapnel and using aerial observation.  A surprise salvo of shrapnel against a registered target (ie without ranging) could also be very effective and low airburst shrapnel was also effective for neutralisation.  However, it was recognised that damaged guns could be easily replaced.  It was also recognised that ‘destroyed’ batteries should occasionally be engaged because sometimes the observer was wrong in the assessment and sometimes positions were re-occupied.

Artillery Intelligence

German artillery concealment and deception practices were also recognised.  These stressed concealment, including tracks, dust from muzzle blast, and earthworks.  They would try and keep firing when under fire, stopping when CB range was altered.  If an empty position was engaged they would quickly put in a gun to fire a few rounds.  Dummy batteries were also used but the British recognised these because air reconnaissance didn’t reveal the distinctive marks of an active position.  The Germans also tried, unsuccessfully, mechanical flash reducers and in July 1915 one German formation banned howitzers and mortars from firing at night because of flash spotting.  Dummy flashes and flash reducing powder was also tried.

For artillery intelligence the key ‘tool’ was the HB Register.  It recorded details of each identified HB and its activities, and cross referenced to the aerial photograph index.  One use of the register was to help identify the HB that was firing at a particular area, later called ‘shelling connectivity’.  The first printed HB maps were produced just before Second Ypres in April.

The Gun Position

Aerial reconnaissance and HBs located instrumentally meant that the calculation of firing data had to be done on the gun position.  The Battery Commander’s Post became the place where firing data was produced.  Adjacent to it were the battery’s telephone exchange and the RFC wireless.  Ideally, these would be three separate shelters, side by side, the BC’s in the middle with hatches into the others on either side.  Details about the evolution of technical fire control are in the Fire Control pages for World War 1.

WORLD WAR 1 - 1916

Organisation

By the beginning of 1916 the heavy artillery was still expanding rapidly and in addition to the HAR Groups there were Corps and Army heavy artillery, mostly organised into RGA brigades commanded by lieutenant colonels.  The MGRA at GHQ proposed that all heavy artillery should be allotted to Armies, which in turn would allot RGA brigades to corps.  This was accepted although the General Staff decreed that the ‘brigades’ should be ‘groups’ commanded by lieutenant colonels.  The implication being that batteries would move from group to group as required instead of brigades with a fixed assignment of batteries.  The plan therefore, was that each corps would have two Heavy Artillery Groups (HAG) normally of five batteries with two further HAGs for each Army.  This was broadly consistent with War Office planning for a 100 divisions, each with 16 heavy and siege batteries per standard corps, however, the BEF considered that 19 batteries was the minimum and 27 the goal, both figures including 6-inch guns, but continuing to assume all batteries had four guns.

The positions of GOCRA of the previous Army level HAR Groups were abolished but a new position was created in each corps.  This was the Corps Heavy Artillery Commander, of equal rank but subordinate to the corps GOCRA.  They had a very small staff, and were organisationally part of each corps HQ, although geographically they were often separate.  All these arrangements were approved on Z-1 day of the Somme battle, along with authorisation to increase the 60-pr batteries to 6 guns.  At the end of the year 6, 8 and 9.2 inch howitzer batteries were also approved to increase to 6 guns.  This increased the HAGs to 30 guns and howitzers in a mixture of batteries.

Particular HAGs would be designated for CB, with others delivering other bombardments.  CB HAGs developed ad hoc arrangements for artillery intelligence and deployed further forward than the bombardment HAGs.  Sometimes two HAGs were grouped as a Double Group under one HAG commander, although this seems to have been more usual for bombardment HAGs.  The CB HAG commanders were generally left to conduct the CB battle, under the Corps Heavy Artillery Commander’s direction.  This commander was responsible for both CB and bombardment, and there were no dedicated CB staff, although it appears that a major was locally appointed in some corps.

In April 1916 2^nd Army sought an artillery officer to ‘collect, collate and distribute all information about HBs’.  However, they requested an ‘intelligence officer’ so the War Office arranged for Intelligence Corps officers to be posted.  These proved unsatisfactory due to their ignorance of artillery, reported by GOC 4^th Army, and being intelligence officers they ultimately reported to the Director General of Intelligence at GHQ.  Thereafter to avoid confusion artillery intelligence officers were usually officially called ‘artillery reconnaissance officers’.  This was part of an ongoing disagreement about the status of artillery staff officers in artillery HQs, the sticking point being whether or not such positions were ‘General Staff’ since they had to be filled by artillery officers.

Ammunition

In mid-1916 the No 106 fuze entered service.  This was a reliable direct action (DA) fuze, although it needed immediate modification.  At the outbreak of war the No 44 DA fuze had been the only one available for HE shells (of the RGA guns and howitzers only 60-pr had any Shrapnel).  No 44 was unreliable and in early 1915 No 100, a graze fuze had been introduced, this too was defective and was promptly replaced by a modified version No 101.  The problem with graze fuzes was that they were in effect delay fuzes.  This meant substantial craters and no fragments; such fuzes were useful while the Germans relied on defensive works including overhead protection for their guns.  However, by late 1916 their artillery tactics were changing and the availability of the effective HE DA No 106 fuze became more important.

Aerial Reconnaissance

As outlined above, techniques and procedures for aerial reconnaissance and observation of fire were quickly established and remained generally unchanged throughout the war.  However, Co-operation of Aircraft with Artillery issued in December 1916 by both the War Office and GHQ, was one of a series of similarly named pamphlets that successively replaced one another.  It outlined the types of artillery and the RFC organisation and detailed the observation of fire procedures.  It identified the three artillery tasks and the need for aerial observation for all but particularly the last:

• Barrage fire and attack of targets in the open;
• Bombardment; and
• Counter-battery work.

It stated that successful CB work depended on:

• Good organisation;
• The allotment of sufficient artillery of suitable natures;
• Efficient observation; and
• Close personal touch between RA and RFC.

The RFC’s duties for CB were:

• Location of the enemy’s batteries; and
• Observation of fire.

The first of these required at least one aircraft over every corps CB area during daylight, weather permitting, as an artillery patrol to locate targets.  Patrol aircraft could engage HBs but were reminded that information gathering may be of greater value to the corps than engaging a single HB.  The duties of the artillery patrol were to:

• Locate new HBs and report those seen active;
• Reconnoitre all known HB positions, particularly those only roughly located, and fix their exact positions;
• Observe fire on active HBs;
• Locate new trenches, MG positions and enemy works; and
• Record movement seen on roads or railways and engage it if in artillery range.

The RFC squadron recording officer debriefed and recorded information from pilots and maintained an HB record book.  The squadron commander was responsible for obtaining whatever aerial photographs the CB commander required, and noted that photography was the basis for good CB work.  By the beginning of 1916 some 50 aerial photographs per day were being provided for an army front.

Wireless receivers, with two operators having the sole duty of taking  messages, were to be provided to:

• HQ Corps Heavy Artillery;  
• HQs of HAGs;
• Heavy and siege batteries, including detached sections;
• Divisional artillery HQs;
• Squadron HQ (2 sets), one with the squadron the other centrally located to receive all reports, it was connected to the squadron by cable; and
• Balloon companies.

Batteries were responsible for getting the wireless messages to where they were needed, ie the Battery Commander’s Post on the gun position.  In practice it seems to have been normal for the BC’s Post to have the RFC wireless and the battery telephone exchange adjacent to it.  The battery was responsible for transporting the RFC element.

Wireless was the main method of air-ground communications, although if two aircraft were less that about 1000 yards apart they could jam each other’s transmission.  To reduce confusion a 'clapper key' was introduced for Morse signalling, this gave each key a distinctive pitch to its Morse signal.  However, Verey lights and signalling lamps were still used, their problem was their very limited bandwidth and hence vocabulary.  Ground-air communications relied on white strips 12×1 foot laid out on the gun position.  This meant the observation aircraft had to fly to see the gun position.  The skill was to avoid having to do this by having well-practised methods, such as positioning the aircraft so that it could see when the guns fired and knew the time of flight and hence when to observe for the fall of shot.  Of course the type of aircraft used had an observer/wireless operator as well as a pilot.  However, there were mixed views as to whether the pilot or observer should be the artillery observer and this persisted throughout the war, some squadrons used the pilot, others the observer.  The reason for using the pilot was that he was the one who positioned the aircraft in the right place at the right time to see the fall of shot.  

Field Survey Company

In February 1916 a Field Survey Company (FSC) RE was formed in each Army, these were an expansion of the Topographic Sections RE that had evolved from the RE Ranging & Survey Section.  In addition to topographic survey and map supply, each FSC included an Observation Section for flash spotting and two Sound Ranging Sections.  Each of these sections was normally commanded by a RE or RA captain. 

An Observation Section was divided into groups of survey posts, with the FSC HQ controlling and coordinating all observations.  However, this quickly changed to each group having its own plotting centre that did its co-ordination and collation, and at least three survey (ie observation) posts to produce accurate HB observations from which the plotting centre produced locations. A Group had one officer and totalled 29 all ranks, at the end of 1916 this increased to three officers and a total of 72, including 12 men for each of four survey (ie observation) posts.  This strength recognised that observation groups were seldom withdrawn from the front and needed enough men for rotation and relief.  A sound-ranging section had three officers and totalled 21 all ranks.

In May 1916, a better method of flash-spotting synchronisation was invented in the field by Lieutenant Hemmings RE (Canadian by birth but an officer in the British Army).  The flash and buzzer board, using a remote telegraph key (at each survey post) caused its lamp to light on a board in the group plotting centre.  The idea being that flash-spotting posts would tap the flashes they were observing enabling quick determination of which posts were observing the same flashes.  The initial model didn’t work because of insufficient line current to light a bulb but this was fixed by using relays and adding a buzzer obtained from Post Office engineers in London. 

Each post’s buzzer had a different pitch, this enabled identification of the first post to report and appointed to lead, other buzzers were then switched-off.  The lead post’s buzzer could be heard by the other posts helping them to pick out the same flashes.  Once all the lights were flashing together the plotting centre ordered the posts to report their angles to the flash source.  Production versions of the ‘flash and buzzer board’ reached all flash-spotting groups by November 1916.  It significantly improved the effectiveness of flash-spotting.

Figure 6 - Flash and Buzzer Board

13¼×10×16½ inches high, the early versions only supported four posts later ones, as below, supported six.

A captured German instrument with a prismatic telescope was copied as the ‘Trench Theodolite’, it was a compact instrument but only a few were produced.  An improved version was designed by Major Henrici RE, called ‘Theodolite, Flash Spotting’ it had ×6½ magnification and 6½° field of view, with both horizontal and vertical scales that could be read to 1 minute.  It became widely used.

The cross observations from the accurately surveyed observer posts were reported as angles and times to the group plotting centre.  These used plotting boards with a gridded chart or map and cat-gut strings with lead weights, instead of drawing lines, to plot the intersection of observations and hence the location of the HB.  Arcs (degrees and minutes) for each post were permanently marked on the plotting boards.  All known HBs were shown and marked with their HB number to quickly identify active batteries.  HB locations were given an accuracy rating: P – within 50 yards; Q  – within 100 yards; R  – within 150 yards, these distances also being used by sound ranging.

Figure 7 – Flash Spotting

Observers reported their angles which were plotted.

At the beginning of 1916 sound ranging was still not particularly effective.  The French instruments were being used but to increase capability some aural observers were deployed, there’s no indication that they had any noticeable success.  The problem was that the instrumental carbon microphones were ineffective because they only detected higher frequency sounds, including those of supersonic shells and bursting shells, but not the low frequency sound of guns firing.  The French had tried various techniques but none were notably successful. 

However, in 1916 the British sound rangers made a series of advances that soon led to an effective system.  First was the invention of a low frequency 'Tucker' microphone (named after its inventor Corporal Tucker) that detected the pressure wave of a gun firing.  This pressure wave had first been noticed by a French researcher, Professor Esclangon, using an aneroid barometer.  A high frequency wave had little amplitude and oscillated rapidly, whereas a gun firing wave had significant amplitude and was a single long wave with its shape depending on the type of gun. 

The Tucker microphone comprised a container of 20 – 30 litres size that was sealed apart from a small window, across this was a red hot electrically heated platinum wire.  When a pressure wave reached the wire it cooled it, this changed the wire’s resistance and could be signalled on field cable to the string of an Eindhoven galvanometer several miles away.  These strings were illuminated to create a very narrow shadow onto moving photographic film with a time base.  When each string vibrated the shadow of its movement was recorded as a continuous line together with the timescale.  It also gave a picture of the pressure wave that could identify the type of gun.  Initially the recording device was mounted in a truck and the film passed straight into a darkroom for processing on the same vehicle.  There was continual improvement in film processing speed, about 500 feet of film was used daily. 

Figure 8 - Sound Ranging

However, the microphones were vulnerable to interference from wind turbulence.  This was solved by using brushwood or camouflage screens around the microphone.  Interestingly, the Germans captured some microphones in 1918 but couldn’t get them to work properly because they didn’t realise the significance of wind turbulence.

The recording equipment was switched on when an advanced post listening for HBs firing reported it.  This post had to be 1000 – 2000 yards forward of the microphone base, depending on whether there were one or two advance posts.  This ensured that recording was switched on at least 2 seconds before the sound wave reached its nearest microphone.  One issue was that the cable between microphone and recording equipment had to be a pair because earth return wasn’t satisfactory.  It also required a low resistance (250 ohms) circuit, meaning a heavier than normal grade cable.  This amounted to some 5 tons of S.II cable for each sound ranging base. 

As with the flash and buzzer board the microphones were manufactured by the General Post Office.  The first 20 sets of recording equipment were made at the Institut Marey in France but subsequently the Cambridge Scientific Instrument Company undertook production for British service.

By September all sections had the new equipment.  With effective microphones the sound ranging ‘bases’ – the microphone array, also changed.  Mid-year ‘regular’ base layouts were introduced, with the microphones in a straight line equidistant apart.  A typical ‘base’, had six microphones across about 7000 yards and 2500 yards behind the front.  The regular base meant that the ‘breaks’ on the microphone film for a particular sound source were in a curve, making a set easier to identify and enable a standard set-up for the plotting boards.  Trials determined that it was better to deploy the microphones behind the British gun-line because there was less likelihood of the field cable being cut by enemy fire.  However, for best results sound ranging required that any wind was blowing from the HBs towards the microphones and strong winds in the opposite direction meant that the sound of HBs did not reach the microphones.  This was a problem because on the western front the wind was normally off the Atlantic and hence West to East.

Of course the data captured on the film had to be converted to a location.  This was done by measuring the time of arrival difference between each pair of microphones (called a sub-base).  Time of arrival difference scales for each sub-base were marked around the edge of a 1:20,000 scale plotting board, this involved calculating (using logarithms) the angles between the asymptote and sub-base for a set of time intervals.  The maximum interval (sub-base length) was when the sound source was on a line through both microphones, and no interval when the source was at right angle to the mid-point of the sub-base.  Having identical sub-base lengths minimised the set-up time because standard asymptote angles could be used.  Time differences from the film were plotted from each sub-base mid-point using strings of fine gut with rubber-soled weights to keep them taut and the sub-base scales and weights were colour coded. The intersection of the strings was the HB location (if meteorological conditions were standard).  

Figure 9 - Sub-base Plotting

Development of a successful system led to a rapid increase in the number of sound ranging sections.  The new scale being one per corps.  The sections increased in size to 36 including 3 officers.

Gunnery

Finally, by the autumn of 1916 ranging own fire onto HBs (or other targets out of sight to ground observers) and for calibration, see Calibration page, became standard practice.  It meant comparing the plot of the HB position or other accurately known location with the plot of the fall of shot.  For sound ranging this was relatively straightforward although there were various methods.  For flash-spotting it required a line of sight to the shell bursts from at least three observation posts and this was often unavailable.  Nevertheless for calibration it was always possible to have a visible point and instrumental observation ensured accurate results.

The need for ‘map shooting’, engaging targets such as HBs using  artillery fire without ranging, was a inevitable consequence of target acquisition from aerial photographs (once it became possible to deduce target coordinates from a photo), sound ranging and flash-spotting.  In addition to ballistic data in firing tables it required two services, survey to accurately fix and orient the CB batteries and meteor to enable calculation of accurate firing data.  Accurate map shooting was not sufficient for destruction but was sufficient for neutralisation.  Survey was provided to RGA batteries from early 1915, see Mapping and Survey page.  Also in 1915 there was some use of locally measured meteor data and relatively complicated calculations, but by late 1915 new range tables started being issued for the various guns and howitzers and in early 1916 meteor telegrams started being distributed, see Meteorology page.

Delivery of No 80/44 fuzes meant that high airburst HE shells could be cross-observed in daylight, and their position plotted, this made possible observation of fire against an out of sight HB.  It meant that batteries (or other targets) located from air-photographs or other means and their position coordinates fixed could be ranged.  There were two methods for airburst ranging, one was merely to shorten the fuze length so that the shell burst on its trajectory to the target.  The other was to burst the shell high enough above the target for the burst to be visible. However, with this ‘non-rigidity’ of the trajectory meant that the resulting fire aimed at the ground was inaccurate and the gunnery data and techniques to correct for it were not available in 1915 -16. 

Artillery Intelligence

The Field Survey Company HQ at an Army HQ had a compilation section that provided the Army Compiling Office.  They provided Army level HB collation and were responsible for issuing a fortnightly HB list and CB map of all Active HBs in the Army’s area.  Previously RFC, Flash-Spotting, various artillery HQs and General Staff (Intelligence) had all circulated their own HB lists.  Intermediate reports from RFC, etc, were still issued, although the Compilation Office also undertook air-photo interpretation, but the RFC reports were superseded once the collated Army list was issued.  The HB List provided a map sheet reference and was used by batteries to produce firing data.  The CB Map showed HBs in relation to topography (ie map detail could be inaccurate) and were designed for use by aerial observers.  Later maps were markedwith the HB arcs of fire deduced by artillery intelligence.  When combined with the battery's maximum range it gave the HBs' areas of influence, which determined which HBs should be engaged to prevent them interfering with a particular operation.

However, artillery intelligence was concerned with the artillery point of view and making deductions from the information supplied in order to make the best use of CB fire.  By summer 1916, when HAR Groups and assorted RGA brigades were replaced by HAGs the organisation was found to be inflexible, and Army HQs were not the right level for organising and controlling CB.  Corps, with their new Corps Heavy Artillery Commanders, began establishing their own CB organisation, some appointing a major as the CB Officer.  Each corps having its own designated CB area, recognition that corps was the appropriate level for CB operations.

The Somme battle provides an interesting case study in CB, bearing in mind that map shooting was still emerging.  Between 26 June and 28 August the German 1^st and 2^nd Armies lost 1068 of 1208 field and 371 of 820 heavy guns captured, destroyed or made unserviceable.  The problem was that before Z-Day (1 July) poor weather that limited aerial observation and only two German divisions had had heavy losses of artillery, this was not enough and was a primary cause of the failure on 1 July.

WORLD WAR 1 - 1917

Organisation

By late 1916 the heavy artillery organisation had been settled as had the technical organisation of sound ranging and flash-spotting.  However, the overall organisation including the vital artillery intelligence and CB control arrangements were still not right, although there was recognition that corps was the key organisational level. 

By the beginning of 1917 RA Reconnaissance Officers were established in various HQs as artillery intelligence officers.  These were Staff Captains at each army and corps, with Staff Lieutenants at GHQ, each division and HAG.  Most importantly Counter Battery Staff Officer (CBSO), a GSO 1 (Lieutenant Colonel) position, was created on each corps artillery staff together with a junior officer and a team of clerks, air-photo interpreters and draughtsmen to form a compilation office.  A Staff Captain was added later in the year. 

Good practice CB processes were sufficiently understood for GHQ to issue direction.  In February GHQ Artillery Notes No. 3 Counter-battery Work were issued.  Its introductory statements included:

“During the course of the present war the importance of counter-battery work has become more and more accentuated.  For just as artillery forms the main support of the offensive, so also is it the strongest weapon of defence.”

“Destruction of artillery is a most important factor of success, from both a moral and material aspect.  Every hostile battery destroyed is one step gained, and destruction of the enemy’s artillery must not be left to the eve of battle, nor neglected until the enemy attacks.  The struggle against hostile artillery must therefore be the constant consideration of Commanders.”

“Counter-battery work is not a matter of spasmodic effort, but is a continuous operation depending for success on accuracy of fire, continuity of plan, unremitting study and firm control.”  It went on to say that all guns and howitzers may be used for CB work according to the requirements of the tactical situation.  It also stressed the need for a permanent and methodical CB effort, for effective communications between fire units and target acquisition elements and the importance of air observation.

Artillery Notes No. 3 formally established the primary responsibility for CB action at corps level, with the GOCRA at Army HQ responsible for coordinating CB fire across corps boundaries.  This GOCRA worked directly with the corps wing commanders to coordinate RA and RFC activity, and with the army General Staff (Intelligence ) and Army Field Survey Company for all matters affecting artillery intelligence.

GOCRA at corps issued orders to the corps heavy artillery and any field artillery under corps level command.  He coordinated with the corps squadron and balloon company commanders for combined RA and RFC action, these RFC commanders were also his technical advisors.  He was responsible for the corps CB programme and control of CB activity.  The Corps Heavy Artillery commander had executive command of CB activities including allocating resources.  He was assisted by the CBSO.

Air Observation

In 1917 the B.E.2c started being replaced as the primary reconnaissance aircraft by the R.E.8.  Worryingly, 1917 opened with the RFC being forced into air inferiority by a new generation of German aircraft.

However, by the end of 1917 both gunners and airmen felt that the system was less than perfect.  Mead, an experienced army pilot and commander of the mid 20th century, identified several problem areas:

• Communications, wireless telegraphy to the ground and visual means to the air meant that aircraft had to 'visit' the battery and then return to where they could observe.  Transmission quality was poor due to interference, background noise and jamming, it was also 'voiceless' hence there was no 'human touch'.  Ground antennas, being 150 feet long, were prone to damage.  This led to a loss of confidence between the officers aloft and those on the ground, exacerbated by lack of a common military background and usually being unacquainted with each other; the practice of pilots visiting batteries had become frowned upon by the RFC despite being identified as necessary in Artillery Notes No 3.
• Observation skills, observing is not a natural human skill, it requires training and practice.  Air observation requires its own special skills, especially when done from a few thousand feet without the aid of binoculars, with varying viewing angles and the need to take account of varying light conditions and camouflage.  Although observer training improved in 1917, in essence it was 'on the job' and without the benefit of an experienced mentor, conditions that would never be allowed for an artillery observer on the ground.  Inexperienced observers being notoriously prone to 'fall of shot optimism'.  The UK Official History commented on this with regard to the Arras campaign in 1917, all too often reported target rounds were anything but that.  The air observers' problems were of course exacerbated by the need to fly the aircraft (if they were the pilot as was increasingly the practice), and be alert for enemy aircraft and AA fire, with the added risk from the trajectories of friendly and enemy artillery fire.  All hardly conducive to intense observation of the ground.
• Slowness, the communications delays and the time taken to move the aircraft and undertake the work in the battery meant that all too often flying for two or three hours to engage two or three targets.  While possibly acceptable in 'siege conditions'  the prospect of mobile warfare in 1918 meant that such times were not going to work in a fluid situation.
• Gunnery understanding, the gunnery system was not robotic, observers needed to properly understand how it worked to make best and efficient use of it.

Nevertheless there were some outstandingly effective air observers.  In 1916 General Rawlinson, commanding 1st Army had commented that "the large proportion of effective shoots carried out with aeroplane observation have been the work of a few men".  However, while its important to recognise the weaknesses in the air observation arrangements, it must be remembered that this was only one form of aerial target acquisition, photography was another matter altogether.

Technical Developments

The effect of weather conditions on sound ranging were understood early in its use.  In 1916 a wind section had been established to gather data and support research including collation with routine meteor provided to batteries.  A circular base was deployed in the rear area and explosions fired at its centre.  The results provided data about the effects of temperature on the speed of sound.  This continued throughout 1917 with data collected and analysed, this revealed that wind and temperature conditions up to about 500 feet above ground were important, and that corrections for these variations could be calculated and applied when converting time to distance (the speed of sound varies).  This significantly improved the accuracy of sound ranging results.  Subsequently, a small sound ranging team joined the meteor staff at each Army HQ and produced sound ranging meteor telegrams. 

Late in 1916 W Section, responsible for sound ranging experiments and trials, used a curved regular base instead of a straight line one.  Eventually the ideal curved base was recognised as 35 seconds (about 11,800 metres) radius and microphones 4½ seconds (about 1500 metres) apart.  This became the norm in 1917.  Also in 1917 bromide paper replaced film for recording, it was about half the price.  It was also faster to process which enabled automatic processing and this was introduced the following year.  The section increased in size to 43 including 4 officers.

The French had developed two new instruments for flash-spotting.  These were the Longue-vue Monoculaire for daylight use and a binocular for night, both used the same mounting.  The former was a prismatic telescope with excellent optical quality, a 3-inch object lens and triple eyepiece giving ×32, 23 and 16 magnification.  It was adapted for British use by fitting it to a British mounting and adding graticules, although the telescope was a bit too heavy for the mounting.  They came into widespread use in late 1917 and were used by all groups by mid 1918.  By this time groups had increased in size to 82 including 3 officers.

Figure 10 - Longue-vue Monoculaire

Other artillery intelligence methods were also being used.  Shell fragments, recovered by crater examination had become a useful aid to identifying the type of gun or howitzer that fired them.  However, it is not clear if crater examination extended to deriving the line of fire and angle of descent (and hence range), or whether shrapnel time fuzes were routinely recovered to determine the range, which would help connect areas shelled to the firing batteries.  Conveniently the German time fuzes used with shrapnel were marked with ranges not time as British ones were.  Wireless interception, using ‘cross-observation’ against German aircraft was also developing.   It enabled identification of connections between German air observers, guns and areas shelled.  Being able to link guns, observers and areas shelled helped reveal German organisation and boundaries.

Artillery Intelligence>

Artillery Notes No. 3 identified 8-inch howitzers and upwards as required for CB destruction.  6-inch howitzers were effective for neutralisation and field artillery was also useful for neutralisation, particularly field howitzers (4.5-inch) because they had gas shells.

Artillery intelligence required methodical sifting, recording and studying all information about hostile artillery from all sources.  This was essential for quick and effective CB fire, the main sources were stated as:

• Flash spotting observation posts (cross observation of flashes) and RA observers.
• RFC aircraft and balloons.
• Sound ranging sections.
• Study of maps and air photos, it emphasised the importance of air photographs and their constant study and comparison to identify changes.

The key record was the CB Book with HB locations and target areas.  Location accuracy was also defined, P – within 20 yards, Q – within 50 yards, and R – within 100 yards, which was different to the accuracies used by flash-spotting and sound ranging.

CB Tactics

The identified Principles of Action were:

• destruction of HBs as a daily task, and
• neutralisation on tactical occasions when destruction has not been achieved.

Batteries for CB needed to be deployed well forward in order to engage the HBs likely to be bombarding forward positions.  Howitzers were considered better than Guns for CB, because they were more accurate (actually they had smaller dispersion), and a steep angle of descent.  Destruction required an HB position to be occupied, with CB fire effectively controlled and observed (there was a tendency for fire to drift off target) during both ranging and fire for effect.  Sufficient ammunition had to be used to destroy a battery.  For a properly emplaced (ie dug-in) battery it required 200 rounds of 6-inch Howitzer, 150 × 8-inch, 100 × 9.2-inch or 30 × 12-inch.  These quantities could be reduced if fire was enfilade or oblique.  Field howitzer could be adequate if the HB not emplaced.  Shrapnel could be used for casualties to detachments and horses.

The object of neutralisation was to paralyse and blind HBs, it was used in both offensive and defensive operations.  The purpose was to stop HBs firing, and was generally only effective while it fell on the target.  This meant it was only useful if there was a tactical need such as when allied infantry was under artillery fire.  During an allied attack all available artillery was used to neutralise HBs when own infantry leave their trenches.  Neutralisation could be planned or impromptu.  Neutralised HBs had to be kept under intermittent fire to keep them so.  Air observation was needed to watch for active HBs, although shelling reports from ground observers or infantry were used with HB records to identify active batteries.  Fire had to be distributed all over an HB position.  Gas was useful for neutralising if conditions were right and sufficient gas could be fired.  RFC and AA guns had to defeat enemy air observation.

Operations in 1917 demonstrated the effectiveness of the CB arrangements.  Unlike at the Somme the previous year sufficient time was allowed pre-Z day for flexible CB programmes, managed on a 24 hour cycle by the CBSOs.  These programmes were responsive to actions of the German artillery and succeeded in destroying a significant proportion of HBs.  From Z hour onwards the effort changed to rapid response neutralisation against active HBs.

Some indications of effectiveness HB location were:

• After the Arras advance 87% of sound ranging locations were found accurate to 50 yards.
• Messines revealed some 90% German batteries had been correctly located. 
• German withdrawal to Hindenburg Line enabled validation of sound ranging accuracy of HB positions, 199 were accurately located, 32 unlocated and 13 inaccurately located. 

However, there were still some problems.  The Canadian attack at Vimy Ridge, revealed that sound ranging sections and flash-spotting groups took too long to re-deploy.  The main problem was the time taken by the RE Signal Service to re-establish line communications, basically a matter of competing priorities.  The problem was solved by giving cable to the sections and groups and having them establish their own communications.

Third Ypres showed that sound ranging and flash-spotting were too far back, one CBSO took the view that “until such time as the control of these services is placed in the hands of the branch of the service (ie artillery) for whose assistance it is primarily intended, it is difficult to see how any improvement is to be effected.”  GHQ placed sound ranging and flash-spotting into RA for tactical purposes and at the end of the year two RA majors were posted to each FSC to command the sound ranging sections and flash-spotting groups.  In practice they probably each commanded the sections and groups assigned to a single or adjacent corps.

WORLD WAR 1 - 1918

By 1918 the organisation of CB and its associated intelligence was generally settled.  GHQ had also defined the standard conventional map marking symbols for showing HBs (presumably replacing assorted Army or lower level sets) and requiring the Armies’ Compiling Offices to submit and distribute HB maps fortnightly.  By this time the single Field Survey Company in each Army had become a battalion.  Integration of flash spotting and sound ranging also improved by communications between them, this enabled the flash spotters to tell the sound rangers when to switch on recording.

The relationship between Artillery Intelligence and General Staff (Intelligence) had also clarified.  The latter were responsible for documentary evidence about hostile artillery, the former for information about locations and shelling activity.  Intelligence estimates were a joint task.

However, a second edition of Artillery Notes No 3 Counter-Battery Work was issued in February 1918.  It noted that German CB practices were now similar to the British ones and expected redoubled efforts to reduce the power of British artillery and a re-appearance of ‘artillery duels’.  One significant clarification was the statement that the commander of a corps heavy artillery was the ‘executive commander of all heavy and siege batteries allotted to the corps’.  The CBSO was responsible for the organisation and execution of CB work in accordance with instructions of the corps GOCRA.  In other words the CBSO controlled CB fire in accordance with priorities established by the GOCRA using resources assigned by the heavy artillery commander.  This probably made the CBSO the most important lieutenant colonel in a corps.

Corps CB areas were elastic, overlap with flanking corps was almost always needed.  Elasticity was also required in allotting areas to groups and brigades.  In other words rigid organisational boundaries were an anathema for effective CB.

There was also the problem of hostile long range guns (usually railway mounted) firing from positions well beyond the range of normal CB guns.  However, such guns were thin on the ground so it wasn’t an extensive problem.  On at least one occasion a long range gun was located by plotting bearings from two or three different sound ranging bases.  Of course there were only a few British long range guns (eg 12 and 14-inch) able to deliver long range fire to 30,000 yards or more but the meteor data was almost certainly inadequate to do this accurately with map shooting.

When mobile operations started in the summer of 1918, the speed of advance usually outran the 8-inch and 9.2-inch batteries.  In both cases it took several hours to both emplace and un-emplace the guns because both involved digging in the holdfast and filling ballast boxes (9.2-inch), or the Vickers Platform (8-inch).  This increased the importance of 60-pr and 6-inch Howitzers.  Of course sound ranging and flash-spotting also took time to re-deploy but training in the winter 1917-18 had reduced base deployment time to under 12 hours in reasonable conditions.  However, mobile operations also tended to present more opportunities for ground observers because during an advance HBs more frequently came under direct observation from RGA observers.  Some heavier RGA batteries also used captured German guns, particularly the more mobile ones.

Early in the year the RGA re-organised for the last time.  Groups, with a changing cast of batteries, were replaced by brigades with standard organisation and permanently assigned batteries:

• Mixed Brigades, with the primary task of CB fire, comprising two batteries of 60-pr Guns, two of 6-inch Howitzers and one each or 8-inch and 9.2-inch Howitzers.
• Mobile Brigades, for general use and suited to mobile warfare, comprising two batteries of 60-pr Guns and two of 6-inch Howitzers.
• Howitzer Brigades, for barrages and bombardment, with four batteries howitzers.

Heavier artillery was also brigaded, 6-inch Guns and larger and 12-inch Howitzers and larger.  These Army Heavy Brigades were both fixed and flexible having a fixed number of batteries and able to take command of the heaviest natures should they be assigned.

Chief sources of information, possibly indicating their order of usefulness, were:

• Air photographs.
• Reports of RFC observers (including balloons).
• Observation Groups.
• Sound Ranging.
• Reports from RA OPs, with at least 1 per RFA and RGA brigade 24x7 (with a No. 5 director for cross-observation).
• Reports of shelling by all units and arms, including start and end times, calibre, nature, number of guns, area shelled, grid bearing to flash or sound, damage.
• Wireless intelligence.

Batteries detailed for CB kept a Target Book with all HBs within arc and range, details for each HB included the Army HB number, and firing data (switch from Zero Line, angle of sight, charge and range reduced to standard conditions).

The CBSO kept complete records of all HB positions using an official form (Army Form (AF) W3710) and air photos sorted and indexed.

The characteristics of CB work were summarised as:

• Destruction of enemy batteries.
• Destruction  of enemy personnel.
• Obstruction of observation and ammunition supply.
• Neutralisation.

To ensure the destruction of an HB it had to be established that the position was occupied (ie to counter German use of alternative positions and deception measures), fire had to be carefully controlled including during Fire For Effect (to ensure it did not drift off-target), and there had to be sufficient ammunition for the  task.  Revised ammunition estimates were provided for destruction.  For single well protected gun pit it required: 100 × 6-inch Howitzer, 80 × 8-inch, or 60 × 9.2-inch!

Air observation remained critical so saving time in air observed shoots was essential.  For slower firing howitzers, such as 9.2-inch, two batteries were ranged simultaneously, and concentrating on one gun pit at a time was the recommended method.  In CB programmes HBs were to be selected in order of priority (importance & activity).  The CBSO sent the following day's CB programme to the corps squadron each evening, with shoots starting as early as possible after first light.  The pilots had to study the air photos, read the HB history, and know their own battery positions.  The policy was that two ground observers should follow every air observed shoot.  They were to be told when aircraft reported fire was on target so that they could engage the same HB in future.  If an aircraft had to leave a task then the CBSO arranged for another aircraft, balloon or order a battery to fire without observation.

Looking ahead the 1918 edition of GHQ Artillery Notes No 3 also considered CB in mobile operations.  In these conditions it was likely that HBs would be unprotected.  This meant lighter artillery could be used for CB.  Concentration shoots with or without air observation could be used although the first was only justifiable when time is short, aircraft numbers, own batteries numerous and target very important.  Shoots could be neutralization or destruction.  The tactic of concentration shoots (using several batteries on one target at the same time) was a recent innovation and necessary when conditions prevented the use of air observation. 

CB shoots were to start with two salvos using instantaneous fuzes, but preferably 60-pr shrapnel for anti-personnel effect.  This was to try to catch the gun detachments before they took cover, but also to condition them to taking cover and making them vulnerable to using such fire to achieve neutralisation.  Surprise bursts of HE, but particularly shrapnel, was to be used at night after a destructive shoot in bursts at irregular intervals, the purpose being to catch repair and replacement activities.  During destructive shoots some fire was to be at neighbouring batteries to catch spectators and at flanks and rear of batteries under destruction fire. 

Obstructing ammunition supply was to be achieved by destroying or blocking the roads, railways and bridges likely used by for resupply.  However, tactical requirements limited destruction of roads when an advance was planned.  The enemy’s supply to batteries was to be made hazardous and costly by harassing fire (HF) ‘to effect physical and moral damage’.

Neutralisation was a temporary expedient designed to paralyse and blind, by sudden and violent fire, HBs that have not been destroyed.  It was required in both defence and offence.  Normally it was the task of medium guns and howitzers, assisted by divisional artillery if available, but heavy howitzers could be used.  In defence neutralisation was during enemy preparatory fire and against enemy covering fire when the enemy infantry left their trenches.  It was essential to relieve allied infantry from enemy fire.  Once mobile operations started in the final months of the war aircraft also proved useful for neutralising HBs.

Similarly in offensive operations, allied infantry had to be protected from enemy fire when they left their trenches.  Planned neutralising fire was to be on all HBs, both known and suspected.  It was also to cut communications and engage OPs.

The need for neutralisation to silence active batteries overrode the daily destruction programmes.  Neutralisation zones were allotted to groups and batteries for use when general neutralising fire required.  Neutralisation had to be rapidly applied with fire distributed over target, area it could use map shooting and methods of fire kept varied to ensure it was unpredictable.  Gas was particularly suitable for neutralising HBs immediately before and during an attack.  It could keep an HB silent 2 or 3 days.

The first (and only) edition of Artillery Notes No 7 was also issued in February 1918.  It identified CB work as an important part of counter-preparation to hinder the enemy’s preparation for attack.  Key points were the continuity of CB work on organised lines and “relentless energy in CB intelligence and persistent destruction of HBs in accordance with resources available”.  When the enemy’s intention to attack became clear or suspected CB work became exceptionally important because continued losses to the fighting power of enemy artillery helped maintain allied fighting power.  However, the moment the enemy attack was launched artillery attacked their infantry with a consequent reduction in CB work.  CB was to use gas, and enemy supply dumps, and the road, rail, tracks used to support artillery were also to be attacked.

Although Sound Ranging Sections and Observation Groups had been used for observation of fire since 1916, Co-operation of Sound Ranging Sections and Observation Groups with Artillery (Provisional) was issued by GHQ in November 1917.  It dealt with using these to range against any known point using a single gun or several batteries, and for calibration.  Calibration always used ground-burst but ranging could be air or ground-burst. Ranging rounds were normally fired at 1 minute intervals.  Three rounds were to be used for ranging, then 8 rounds to verify the ranging, then fire for effect.  Airburst could be used with an Observation Group to range points on the ground hidden by intervening terrain.  However, it only required the angle of sight to be lowered for fire for effect.  It was cancelled and replaced by Ranging with Observation by the Field Survey Company in May 1918.  Sound ranging could be used to range any point within 5000 yards of the front line.  Ranging was to be with one gun of a calibrated battery, but after 20 – 30 rounds fire for effect, there was to be an observation check.  However, it also corrected the gunnery for airburst ranging, a correction for non-rigidity as well as lowering the angle of sight had to be applied.

Writing after the war Broad provided a comprehensive description of CB in the last year of the war.  He defined CB work as ‘a tactical operation which is actively continuous day and night, whenever opposing forces are in contact’ and quoted Ludendorff as reporting that Allied CB destroyed 13% of German guns in one month in 1918 on the Western Front.

He explained that the CBSO was a corps staff officer located close to heavy artillery commander, usually in the same house.  The CBSO issued direct executive orders to units that were part of a subordinate formation.  The CB office, comprised the CBSO, three junior staff officers with clerks, draughtsmen and photo-interpreters divided into Operations and Intelligence branches and operated continuously 24×7 when a corps was in the line, and corps seldom rotated out of the line.  The office was divided into Intelligence and Operations branches.

Intelligence Branch:

The branch was responsible for collecting and disseminating all information about hostile artillery, making deductions from information and co-ordinating intelligence activities of CB office, survey units and RAF.  All located HBs had a zone number. 

From their analysis they either forecast movements of enemy artillery during battles or forecasting enemy intentions from the ‘attitude’ of his artillery.  It required tactical and technical knowledge of enemy artillery, and ability to appreciate ground by map reading and indicators from photos.

They recorded:

• All information related to known or unknown HBs, either on suspect map and card index for unlocated battery or record sheet for located battery. 
• Logs of all shelling reports.
• HB record sheets cross-referenced to air photos.
• All new ‘suspicious’ work recorded as suspect.

Some offices maintained a Harassing Fire target map, because in some corps the CBSO was responsible for HF planning while in others it was the G Intelligence Branch responsibility.

Broad  also emphasised the significance of air reconnaissance as the basis for all CB intelligence.  He wrote that the air-photo was the eye of CB artillery, it contained almost everything that was collected piecemeal from other sources, but was less timely and only failed when HBs were completely concealed and inactive.  Operations photos were taken at 10,000 ft, reconnaissance (mainly used at Army HQ) was at 17,000 ft to cover a larger area.  New reconnaissance photos were normally required about every 3 days on a stable front, more if the enemy were moving.  By this time several hundred photographs per day were being provided for an army front.

The squadron artillery officer linked the CBSO with the aerial observer, he interviewed all observers after landing.  In addition to the corps artillery squadron, the Long Range Gun Flight from the Army Wing was attached to the Corps Wing, it had ‘fighting machines of the first class’ for observation inside enemy lines.  Since it operated deeper than the corps artillery squadron it's aircraft were fitted with receiving sets as well as send (this meant batteries needed sending sets) so that it didn’t need to visit the battery to see ground signals.  Broad wrote that balloon work was almost entirely connected to artillery, although in Europe troop movements could not be seen unless they were in large numbers.  In Palestine, where visibility was much better it was possible to see single Turks at 6000 yards.  However, balloon observers were not very effective for producing accurate locations, but could range guns on to visible targets in the forward area.  Nevertheless, they were good for collecting intelligence about HB firing activity, particularly at night, and for providing confirmatory evidence.  Normally a balloon was affiliated to a battery for immediate response.

He noted that sound ranging needed to be under centralised control because the position of detachments depended on the enemy’s artillery groupings and not own corps or other boundaries.  Time to provide an HB location was 5 minutes to half hour depending on difficulty.

Artillery intelligence revealed the 1918 German spring offensives.  Information came from air photos of guns and ammunition dumps, deployment including noise at night, prisoners (an artillery reconnaissance party was captured) and the Secret Service (rail movements in Belgium carrying artillery).

Broad also noted that wireless intercept (two wireless compass station companies per army) was useful, particularly against aircraft.  It enabled fighters to be guided against German observation aircraft.  Skilled operators were able to identify individual observers, and hence track formation movements, and make shelling connections.

The Operations Branch used:

• HB Plotting board with plotting strings and showing own observers and their observation arcs, and HBs, it enabled the staff to identify active HBs.
• Fighting map, showing own batteries and their arcs of fire, and HBs.
• Suspect HB map, maintained by Intelligence, with a card index for each map square.
• Activity charts, map showing HBs and their activity.
• Shelling connection map, connecting HBs with their targets.
• Own gun in-action board.

The Branch was responsible for:

• Daily programmes for destruction of HBs.
• Neutralisation to stop HBs firing.
• The continual attack of HBs, this was a most important policy throughout war and was managed through a daily programme of fire observed from air.

Concentrations could substitute for observed shoots, and were most frequently used during battles, they were very effective against morale.  They could be by a few batteries or hundreds of guns, but shoots had to be synchronised.  Converging fire (ie dispersed firing batteries with different azimuths) was notably useful.  It could be achieved by using several batteries with one gun from each against an HB to maximise converging fire.  Concentrations were also used by air observers against HBs firing.

During battle CB sought temporary superiority over enemy artillery, obtained chiefly by surprise and intensive neutralisation.  CBSO produced a programme issued to each CB brigade, kept a reserve and prioritised targets.  Only 2 or 3 guns were needed to neutralise an HB.  CBSOs liaised and coordinated with each other and their CB targets not restricted to their own corps boundaries.

Another former CBSO, the Canadian Major General AGL McNaughton, also wrote a post war account of CB.  He noted that German artillery was invariably organised and fought on divisional front, in consequence they had great difficulty in massing adequate fire.  Their artillery intelligence was also collected and coordinated on divisional front, making it difficult to quickly pass information between adjacent formations, and they did not seem to have a suitable artillery chain of command to fully exploit it.  This highlights the significant difference between British and German CB, the latter retained a system that the British had recognised as inadequate by mid-war.  German thinking seems to have been governed by doctrine concerning 'unity of command', a principle never adopted by the British Army, which applied 'unity of effort'.

He also emphasised the importance of aircraft, including the zone call and reconnaissance role, noting that in positional warfare 30% of CB information was from air.  However, he also noted the disadvantages: flight meant observation was intermittent and observers could not give their whole attention to a task.  Air Photos with skilled interpreters revealed much information including precise position and whether or not an HB was active.  Camouflage was overcome by stereoscopic photos, comparisons, and ‘special colour plates’.  But favourable weather was needed, and it took 6 – 24 hours to interpret and circulate information.

Artillery liaison officers at infantry brigade HQs were important, they reported own troops information, any intelligence derived and were the conduit for reporting HB shelling activity.  The artillery officer at RFC squadron HQ, was the technical assistant to the squadron commander and represented the CBSO.  He promoted cooperation and solved problems.

Secret agents and repatries were useful for information about supply dumps, centres of activity, artillery in the rear areas but locations were usually vague, and information took a long time to arrive.  Captured documents usually dealt with the past, but were a useful check on intelligence deductions.  Listening sets did not obtain much information due to secure procedures.  Wireless intercept could determine with fair accuracy whether a station was in the air or on the ground and sometimes gave information of tactical value.  Traffic analysis could give clues to dispositions.  Track charts of aircraft using wireless could give an indication of artillery policy.

The figures in the following table are from Chasseud for 4^th Army.  They show the number of HBs located, many were probably located several times, and the total number reflects the number present.

SUMMARY

Britain entered the war with very little heavy artillery and no established CB procedures.  Target acquisition was limited to aerial observation without photography and very immature procedures for artillery fire with aerial observation.  From this low base a formidable CB system was created that played a very significant part in the defeat of Germany.

Figure 11 - Counter Battery Organisation by 1918

Before 1914 the implications of indirect fire and the need for CB as a major artillery task had not been foreseen.  It developed extremely rapidly during the first 30 months of war.  The critical part was the ‘unseen’ element, guns and target acquisition were essential but they needed the day to day ‘glue’ provided by the CBSOs and their intelligence and operations tactics, techniques and procedures.  Without this the guns and target acquisition would have been ineffective.  

The CBSO position was novel and conflicted with traditional military thinking.  The position was a staff officer for the Corps GOCRA whose office, which had both operations and intelligence functions, was almost always in the HQ of the GOCRA’s subordinate heavy artillery commander, and had executive control over all batteries assigned to CB tasks.  With the benefit of hindsight it can be seen as recognition of the difference between command and control, but at the time some officers thought it heretical.  CB can also be seen as a cohesive command information system, as such it was revolutionary.  

CB was a continuous activity, although its tempo increased before and during offensive operations by either side.  The conditions of the Western Front meant that it was best conducted at corps level to ensure coherent continuity.  Information from various sources  was systematically collected, collated, interpreted  and acted upon.  However, aerial reconnaissance and observation of fire were essential and the critical element was the artillery squadron of the Corps Wing RFC/RAF, particularly for destroying HBs.   However, sound ranging and flash spotting provided the most timely information about HB activity, which was critical during major operations because it enabled neutralization of the HBs having most effect.  The understanding of the difference between neutralization and destruction, and its implications, that became a key characteristic of British artillery seems to have first emerged in CB operations early in the War.

By the end of the war the sixteen British and two Australian and Canadian corps in France (ignoring cavalry) were supported by a total of 78 RGA brigades (75 British (including two Australian batteries) and three Canadian).  The British brigades included 19 Mixed and 17 Mobile, and the remainder Howitzer; the Canadian were one of each type.  In addition there were some 87 siege batteries, with all the 6-inch guns, 12-inch and larger howitzers and all railway equipments that sometimes participated in CB actions.  However, the five British, three Indian, and the Desert Mounted corps in four other theatres (Italy, Macedonia/Salonika, Palestine, Mesopotamia) had only 20 RGA brigades between them, typically with four or fewer batteries, few with more than 4 guns and almost all with 60-pr Guns and or 6-inch Howitzers.  Siege and heavy artillery on this scale was unimaginable in 1914.

On the target acquisition side a total of 35 sound ranging sections and 29 observation groups were formed, all by the Brtish Army.  Six of the former and four of the latter were outside France/Flanders, but none in Mesopotamia.  However, contemporary accounts stress the importance of aerial reconnaissance, particularly photography, for accurately ‘fixing’ HBs, whether or not they had fired from their current position.  Almost all of this was developed during the war.  Flash spotting and sound ranging provided timely but partial information, in contrast the RFC product was less timely but more comprehensive.

The artillery intelligence techniques developed in WW1 provided the foundations for artillery intelligence for many decades.

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