Wednesday, November 30, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 23


Back to Part 22

Conclusion



A report on aerial photography and photographic interpretation written by Major Edward Steichen, an American officer, dated 26 December 1918 referred to a perceived weakness in the British photographic interpretation processes during the war.



‘Frequent cases have been noted where an interpreter who knew nothing about photography mistook imperfections in the photographic plate or print for things recorded by the camera.  Numerous British officers have stated that the French get more value out of their photographs than the British do.  . . .the fact that in the French service the interpretation and all matters pertaining to aerial photography rest in the hands of the French Air Service is chiefly responsible for this superiority.  Edward Steichen, Aerial Photography.  The Matter of Interpretation and Exploitation, (Headquarters Air Service, S.O.S., A.E.F., Office of C.A.S. Photographic Section, 26 December 1918); printed in: Finnegan, Shooting the Front. p. 478.



The initial criticism was valid and the split between photograph processing and photograph interpretation that was formalised in 1916, when the squadron photograph processing sections were established, created a knowledge divide that became more pronounced as the interpretation process moved further away from the photograph processing.  Balanced against this, and the report’s intimation that the RFC/RAF should have controlled the flow of aerial photograph derived intelligence, is the evidence that by 1918 photographic interpretation conducted downstream provided a unique unit focus that helped maintained situation awareness and proved invaluable for battle planning and mission rehearsal.  Rather than control the flow the solution would arguably have been to improve the photographic interpretation training.



At the higher command levels the utility of aerial photography for operational planning was highlighted through Darley’s mosaic in early 1915, and confirmed through Haig’s use of aerial photography in the planning for Neuve Chapelle.



Although invaluable for the higher command and infantry it was the artillery that had the greater dependence on aerial photography.  The First World War was fundamentally an artillery war.  Battery survey and knowledge of the enemy’s precise location became the cornerstone of good artillery operations.  Pivotal to identifying and then targeting an enemy’s precise location was the map.  The only viable source of data for map production was derived from aerial photography through photographic interpretation.  Put simply; no aerial photography, no map, reduced artillery effectiveness.



From the artillery STA perspective, the aerial photograph proved a useful corroborative tool that helped develop confidence in the use and success of the emerging artillery intelligence sources; flash spotting and sound ranging.  Additionally, when compared to the other STA intelligence sources, the aerial photograph had a unique advantage.  German battery detection, location and identification could be achieved without the German guns firing.



For much of the BEF aerial photography proved an invaluable tool, for the artillery it was indispensable.



Next: Part 24 ‘Bibliography


Sunday, November 27, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 22


Back to Part 21


Establishment of the Counter Battery Office at Corps Level

This shift came during the winter of 1916/1917 when as a result of the lessons from the Somme a Counter Battery Office (CBO) commanded by a Counter Battery Staff Officer (CBSO), a Lieutenant Colonel, was formally established by GHQ at each Corps.  November 1916 had witnessed the appearance of the first unofficial CBSO in Three Corps.  Each CBO contained intelligence and operations elements with responsibilities that included; collecting, compiling and disseminating counter-battery intelligence and providing detailed arrangements and issuing orders for counter-battery work (Albert P. Palazzo, ‘The British Army's Counter-Battery Staff Office and Control of the Enemy in World War I’, Journal of Military History, 63:1 (1999:Jan.) p.64.).  Manning levels were modest totalling approximately 12 personnel.  As well as the CBSO there was a Staff Captain, an Intelligence officer and one or two Lieutenants.  The other ranks comprised; two NCO’s, four clerks, three telephone operators and a draughtsman (Palazzo, ‘The British Army's Counter-Battery Staff Office and Control of the Enemy in World War I’. p.64, and Uniacke Papers, Remarks on "Notes on the work of a Counter Battery Office," c. late 1917 (XV Corps), Royal Artillery Institute, U/VIII/9, contained within: Saunders Marble, “The Infantry cannot do with a gun less”: The Place of Artillery in the BEF, 1914-1918, (Columbia University Press – Gutenberg-e)).  The Intelligence officer was one of the new War Office sanctioned Royal Artillery Reconnaissance Officers (RARO) also newly established, at Army, Corps, and Corps Heavy Artillery Headquarters, during the winter of 1916/1917.  The role of the RARO was clearly stated:

‘. . . to carry out special artillery reconnaissance, to study and collate the information derived from aeroplane photographs and maps so far as it affects the artillery, and to keep in close touch with the Royal Flying Corps.  Chasseaud, Artillery’s Astrologers. p. 233.

There was a clear separation in the responsibilities of the Compilation section run by the FSC’s at army level and the compilation conducted by the CBO at corps when it came to aerial photograph interpretation.  The CBO had primacy on determining the ‘fact of’ and activity status of any German artillery identified.  The FSC were responsible for determining the precise location of any identified artillery (Winterbotham, Survey on the Western Front. p. 46.).

For the first time there was an intelligence/operations interface which enabled the results of the intelligence fusion to be acted on immediately.  The success of the CBO initiative was clearly evident at Vimy Ridge in 1917.  Lieutenant Colonel A. G. L. McNaughton the Canadian Corps’ first CBSO attributed the success to the fact that:

‘Each CBO kept detailed scheme diagrams for all systems.  They ensured that Canadian guns were on a common survey scheme to Canadian locating assets.  They had guns for counter-battery tasked to them for extensive periods of time, and kept extremely accurate logs and diaries that permitted the effective engagement of targets by minimising the knowledge gap of the enemy.  In other words, by being highly organised and influential, the CBO was able to take the lead in the fight, which led to such impressive results.’.  A.G.L. McNaughton referenced in: Richard Little, A Short History of Surveillance and Target Acquisition Artillery, Canadian Army Journal, Vol. 11.3 Fall 2008.

The Canadian CBO had correctly identified 173 of the estimated 212 guns that the Germans had available to defend Vimy Ridge, an impressive 83 percent success rate (Bill Rawling, Surviving Trench Warfare, (University of Toronto Press, Toronto, 1992) p. 111.).  Much of the identification success was attributed to aerial photography (Chasseaud, Artillery’s Astrologers. p. 236.).


Next: Part 23 ‘Conclusion

Tuesday, November 22, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 21


Back to Part 20





Actionable Intelligence


The trench map and the processes used to maintain the map’s intelligence currency provided a framework onto which could be fused intelligence from other sources.  This section will explore the evolution of counter-battery artillery intelligence fusion, a classic example of the operational/intelligence interface where aerial photography fulfilled a crucial role in providing and/or corroborating intelligence that could then be acted upon.


The Artillery Counter Battery Role


Not until the end of 1915 was the counter-battery role recognised as a separate tactical operation of the artillery requiring special organisation and co-ordinated intelligence support.  At this stage the compilation of the first large scale 1:10,000 maps had made it possible to accurately plot many of the German artillery battery positions visible on the ever increasing numbers of aerial photographs.  This process highlighted the discrepancies in and between the various counter-battery lists of the period that were being derived from RFC visual reconnaissance reports, RA observation reports, Corps INTSUMS and the fledgling reporting from the flash spotting sections.  A report written in September 1915 had already highlighted the key failing in the contemporary counter-battery intelligence gathering processes:


‘. . . the important and rather difficult point then arises of the proper collation of all results, . . .  Winterbotham, Survey on the Western Front. p. 42.


The First Compilation Section


In an attempt to address the collation issue Third Army set up a Compilation section under the control of its Topographical section in December 1915.  This Compilation section was headed by the previously mentioned Lieutenant Goldsmith.  As well as the study of air photographs, Goldsmith’s stated role was to synthesise and record the counter-battery intelligence from all sources and to disseminate, in INTSUM form, lists of German artillery positions derived from Third Army’s observation and flash spotting sections that he had correlated with the other intelligence sources.  Goldsmith had identified the utility of using aerial photography coupled with the map to corroborate the other available artillery intelligence sources.  With the establishment of FSC’s in February 1916 each army had its own Compilation section.


From early 1916 counter-battery intelligence was rationalised and coordinated at army level.  In each army a weekly list of ‘Active Hostile Batteries’ that consolidated the information from the RFC and the FSC’s was issued every Sunday, coincident with a weekly counter-battery conference where the following were present or represented: General Officer Commanding (GOC) Heavy Artillery, GOC RFC Brigade, GSO Intelligence of the army and the OC of the FSC (Winterbotham, Survey on the Western Front. p. 43.).  These conferences that continued until September 1916 would ascribe a confidence level to the batteries listed, those identified on or confirmed by aerial photography would be categorised as ‘position determined’.  From May 1916 with the weekly lists growing longer and taking more time to plot the details were also transposed onto a counter-battery target map and represented graphically.


Lessons from the Somme


The increase in operational tempo during the Somme and changes to the German artillery tactics exposed the weaknesses in centralising counter-battery intelligence at army level:


‘During this battle [the Somme] German Artillery tactics changed considerably.  Protection gave way to concealment, and positions changed with a rapidity which made an Army compilation out of date almost as soon as lists or maps could be produced.’.  Winterbotham, Survey on the Western Front. p. 45.


GHQ in early 1916 had already recognised the importance of counter-battery intelligence and had imposed an Intelligence Corps officer on the RA at corps level.  Francis Law the Irish Guards infantry officer mentioned previously was one of those officers.  Law had no artillery or intelligence experience:


‘Despite my ignorance of artillery I was given . . . a completely free hand.  Every morning reports reached me from a variety of sources. . . . infantry battalions, brigades and divisions . . . artillery units . . . sound ranging sections [formally established in April 1916] . . . the [RFC] and . . . kite balloon sections.  All gave bearings from their own positions to points behind enemy lines from which gun flashes had been spotted . . .  I set up three large-scale maps, and plotted and recorded relevant information daily.  When several sources had reported enemy activity at a common point I alerted all sources.  I could and did ask the [RFC] to carry out reconnaissances and to photograph suspect areas. . . . I only called for [aircraft] sorties when verification of a target was thought to be vital.  Law, A Man at Arms. pp. 73-74.


Law had found like many of his contemporaries that aerial photography was both a unique intelligence source and a corroborative tool that could be used to validate his other intelligence sources.  With a Sergeant and a small clerical staff he conducted the artillery intelligence fusion role, what is now know as Surveillance and Target Acquisition (STA).  Having determined the targets, what was needed was an evolutionary shift in command and control that would formally link the STA element to the contemporary counter-battery effort.

Next: Part 22 ‘Establishment of the Counter Battery Office at Corps Level

Monday, November 21, 2011

Bloody Victory: The Sacrifice on the Somme


This book has been well reviewed on Amazon and like many of the reviewers the key for me was the way Philpott captures the full extent of the French contribution firmly placing the British and Commonwealth contribution in context. This book is an absolute must for anyone trying to understand why the Battle of the Somme took place.

Friday, November 18, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 20


Back to Part 19


The Distribution of Photographic Prints

The distribution of photographic prints came in three forms, raw, annotated or as part of a specialist product for example a mosaic or stereo pair of photographs.  During 1915, with the RFC Wing photographic sections managing the distribution of prints, the majority went out raw with the recipients expected to carry out their own interpretation and build their own specialist products.  In 1916, following the establishment of squadron photographic sections, an initial proof distribution to the demanding unit/s was handled by the squadron.  A full distribution would be made by the RFC Wing following the transfer of the negatives.  Again, the majority of the prints went out raw.  With aerial photographs now being seen as a direct source of intelligence by the artillery and the infantry, the demand for prints and specialist products soured.  While the print distribution process struggled to cope with the new demand the print production process failed; resulting in frequent delays in the delivery of prints to the subordinate units.  The BEF’s response was two fold, to fill the gap with text reporting and find an organisation that could carry out the necessary bulk printing.  The qualitative improvement in the text reporting noted previously in the First ANZAC Corps INTSUMS during 1916 illustrates the success of the text reporting approach.  The text reporting was structured around the map grid referencing system to facilitate hand written updating of the available mapping:

‘(A). A well defined track evidently considerably used, leading from the communication trench at R.35.a.6.2 ½ . and proceeding in a N.E. direction to R.35.b.4 ¼ .8. where it meets the new trench dug to protect COURCELETTE from the South.’.  Australian War Memorial, FIRST ANZAC CORPS INTELLIGENCE SUMMARY to 6 p.m. on 31st July to 6 p.m. on 1st August ‘17, AWM4/1/30/7 Part 1.

Text reporting also had an unforeseen corollary; not only did it widen the availability of photograph derived intelligence but it also increased the demand for it.  From October 1916 the Army Printing and Stationary Service (AP&SS) had set up a section in Amiens that could produce 5,000 prints a day.  By the end of the Somme each army had its own AP&SS section bulk reproducing prints and specialist products (Chasseaud, Artillery’s Astrologers. p. 227.).  With the printing problem solved by the end of 1916, a corresponding reduction in the text report could have been expected.  This was not the case, text reporting via the updated map was able to reach a wider audience than the distributed print.

The establishment of the BIS’s in 1917 changed the print distribution dynamics and made the RFC squadron the coordinating unit (Figure 10).  With a photographic interpretation function now co-located at the RFC squadron, the form of the distribution changed.  When a photograph reconnaissance aircraft landed, proof copies were printed as soon as the photographic plates were developed.  These copies would be annotated, by the BIO or his staff, showing any changes in the German defences disclosed by comparison with previous HOC photographs and then distributed as a priority, within 30 minutes, to the GS Intelligence officers at Army HQ, Corps HQ and Heavy Artillery, and Division HQ and Artillery.

Figure 10.  Corps Squadron – Aerial Photograph Tasking and Distribution from 1917.
A second issue that expanded the distribution down to Company level when required followed approximately six hours later. (Hahn, TheIntelligence Service within the Canadian Corps 1914-1918. pp. 118-119.).  Figure 11 illustrates a BIS annotated proof vertical photograph.

Figure 11.  Vertical annotated proof print.
Extract from WFA Ypres Map/Photograph DVD


All down the distribution chain, the photographs would on arrival be re-examined and used from the perspective of the receiving unit.  From 1917 on, a soldier at platoon level could expect to carry out trench raid mission rehearsals behind the British line in an exact replica, derived from aerial photography, of the German trench system he was going to raid.  Although preparations did not always go smoothly:

‘Thursday 15 February 1917 - Considerable panic over photographs.  Everyone who is going to have a raid naturally wants photographs of the trenches they propose to enter, but as a rule they let us know about a day before the raid when it is probably quite cloudy.  Hughes, ‘Diary’of T McK Hughes.

The photographs would also have been used by the officer commanding the raid to generate a sketch map that could be used by the other members of the raiding party.  Figure 12 illustrates an aerial photograph derived sketch map used in the Roclincourt area by members of the 2/14th Battalion London Regiment who conducted a trench raid on 19 September 1916.

Figure 12.  Aerial photograph derived sketch map.
"The Body Snatchers": Trench Raid at Roclincourt
 
Battle rehearsal also benefited; prior to their assault on Vimy Ridge in 1917 the Canadians built a scale model of their assault area based on aerial photographs (Figure 13).  Whole divisions were taken to view the model as part of their battle training and preparation.

Figure 13.  Vimy Ridge trench model 1917.

 
Amiens in 1918 saw a proliferation in aerial photographs being made available at company level for study before the attack.  In addition the following products and photographs were issued to the attacking troops:



(a)       A Mosaic of each Divisional front, squared and contoured and freely annotated, for distribution down to N.C.O’s.

(b).      Oblique Photographs of each Divisional front, for distribution to all officers.  Australian Corps Battle Instructions for 8th August 1918, quoted in: Chasseaud, Artillery’s Astrologers. p. 447.



Ultimately situational awareness was facilitated at every level through the availability and local exploitation of aerial photography.



Tuesday, November 15, 2011

The Vosges in 1915


I am currently writing a series of blogs, a result of a holiday in the Vosges Mountains in August 2011 (The Vosges in 1915), exploring the First World War in the region during 1915. For most British Great War enthusiasts the Vosges is that forgotten section of the Western Front, the section where French and German units were sent to rest and recuperate after being mauled elsewhere. This perception is correct for 1916 onwards but the battles in the region during 1914 and 1915 matched the intensity of those further north, in addition they were fought on terrain that makes the British sector to the north appear very benign. Based mostly on French texts the series of blogs is my attempt to introduce the forgotten front to an English audience.

I am in the process of translating 3 bodies of text; a website that describes the activities of the German 19th Reserve Royal Bavarian Infantry Regiment in the Vosges between '21 Jan - 2 Jun 1915' and '1 Jul 15 - 12 Jul 16' and 2 books that describe the battles for the Hartmannswillerkopf in 1915. One that incorporates German sources but focuses predominantly on the French perspective (Diables rouges Diables bleus à Hartmannswillerkopf by Pierre Marteaux (1937) ), the other a German perspective written in German but translated into French in 1934 (Hartmannswillerkopf by Capitain G. Goes ).

Although my oral understanding of French is reasonable the written French word is more of a challenge for me. Up to now I have been using Google Translate coupled with comparative visual editing to overcome the errors introduced through the software’s habit to translate the texts literally. My intention is to carry on with this process but to carry it out in a space (this Wiki) where others, if willing, can help.

Wednesday, November 9, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 18


Back to Part 17

The Uses for Aerial Photography



Foundation Material



During the retreat from Mons in 1914 the scale of the movement involved meant that there was no requirement for detailed large scale maps to support the BEF.  The first demand for large scale detailed mapping came after the battle of the Aisne as the front line began to stabilise.  At this time with no trained surveyors available the BEF had to make do with the inaccurate 1:80,000 French mapping enlarged and redrawn at the Ordnance Survey Office Southampton.  These enlargements were completely unsatisfactory, reproducing and magnifying the errors on the original that introduced gross positional errors.  What was needed was a new field survey of the BEF operational area.  In November 1914 two trained surveyors arrived in France as part of the First Ranging Section RE’s.  These two surveyors were tasked with completing a survey that would enable a more accurate map to be produced in as short a time as possible.  Their field work started on the 25 January 1915 and by the 28 February all the field sheets were passed to the Ordnance Survey for reproduction.  The resulting 1:20,000 scale map was a vast improvement on the previous 1:80,000 enlargement (Winterbotham, Survey on the Western Front. pp. 6-7.).  Its comparative accuracy improved the targeting accuracy of the British artillery and led to demands for accurate mapping of the German held territory.



As mentioned previously, the responsibility for mapping the German-held territory rested with the GS Intelligence. However, the success of the Neuve Chapelle battle map ultimately led to the formation of Army Topographical Sections that became responsible for all map production in their Army’s area of interest.  By the end of 1915 a newly created series of 1:10,000 base map sheets overprinted with the tactical detail of the German defensive positions had been produced.  Aerial photography was the primary source used to derive both the topographical and intelligence detail displayed on the mapping.

Figure 8.  Extract from 1:10,000 scale trench map produced in 1916.



Illustrated above (Figure 8) is a section of the standard British 1:10,000 scale trench map overprinted in red with the German defensive positions.  From 1916 maps of this type would be found adorning the walls in HQ’s and Intelligence sections throughout the BEF.  The BEF now had a coherent framework on which to build a COP.  The real challenge was to maintain the pictures currency to ensure a high level of situational awareness at all levels of the BEF.



Next: Part 19 ‘Situation Awareness

Monday, November 7, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 19


Back to Part 18



During 1915, map production and map revision time, from the start of drawing to receipt of the map ready for use, took about two weeks.  By 1916 the pressure of work at the Ordnance Survey had extended the production timescale out to four weeks (Chasseaud, Artillery’s Astrologers. p. 87.).  As a consequence by the time a map was received at the front it was already out of date.  This issue of currency was appreciated as early as the battle of Loos in 1915 when copies of aerial photographs were circulated so that staff and regimental officers could make hand written amendments to their maps (Chasseaud, Artillery’s Astrologers. p. 108.).  During Loos, Romer (First Army Maps and Printing Section 1915) had his section working through the night producing and printing special map sheets showing the new detail derived from that day’s aerial photographs; these sheets were sent by dispatch rider to the affected units (Chasseaud, Artillery’s Astrologers. p. 110.).

Aerial Photography Limitations

Aerial photography was proving central to maintaining situation awareness, although it was not a panacea but had marked limitations which included; a lack of persistence, weather dependency, and a slow (relatively) response time.  Aerial photography lacked the persistence of visual reconnaissance; it was after all ‘a snap shot in time’.  But to counter this it did provide a permanent record not prone to memory failings, in addition the ability to revisit an area of interest through a collection of photographs, the HOC, gathered over time proved invaluable for change detection.  Weather played a key role in the successful collection of aerial photography.  The poor weather at the end of Third Ypres is probably one of the reasons why II ANZAC Corps’ photograph availability was so low during the period (Figure 15).  Response time proved problematic during the war.  Much has been made of the ‘speed tests’ demonstrated during the Somme where from aircraft landing to processed prints arriving at Headquarters took as little as 30 minutes (Finnegan, Shooting the Front. p. 75.).  It should be noted that photograph processing, printing and delivery was not the whole picture.  Including tasking and flying time, plus time for interpretation and product dissemination; any response would have be extended to several hours or even longer as illustrated by the Lambert (Royal Scots Company Commander 1917) anecdote above.  In the static warfare of the Western Front this was less of an issue, which was tempered further through regular pre-planned photograph collection.  The intent, weather permitting was to photograph the German trench system up to a depth of 3,000 yards every five days, and the counter-battery area every 10 days (B.E. Sutton, ‘Some Aspects of the Work of the Royal Air Force with the B.E.F. in 1918’, RUSI Journal, 67 (1922:Feb./Nov). p. 339.).  During operations this tempo would obviously change.  At Messines in 1917, aerial photographs of the German defences were taken every day during the preliminary bombardment, and the known artillery positions every two days (Chasseaud, Artillery’s Astrologers. p. 304.).  This meant that even outside of operations a regular supply of photographs was available and distributed.

Access to Aerial Photography

As has been outlined, access to aerial photography and intelligence derived from it expanded down through the echelons of the BEF throughout the war.  Figure 9 illustrates the availability of aerial photography to the Australian forces in France from April 1916 to October 1918 based on a review of I and II ANZAC Corps and the Australian Corps daily INTSUMS over the period.  Bearing in mind that the Dominion forces were fully integrated and supported within the BEF, it is probably fair to assume that the availability illustrated is representative for all the Corps in the BEF from 1916.

Figure 9.  Aerial Photograph availability derived from I and II ANZAC Corps and the Australian Corps daily IntelligenceSummaries.

Saturday, November 5, 2011

British Aerial Photography and Photographic Interpretation on the Western Front - Pt 17


Back to Part 16


Evolution of Photographic Interpretation Awareness Training

Following the formal establishment of the photographic interpretation practitioner training in late 1916, 1917 witnessed the formalisation of awareness training.  By June 1917 the following courses, all of which contained aerial photography in their syllabus, were advertised in S.S. 152 Instructions for the training of the British Armies in France (Provisional)  (S.S. 152, Instructions for the training of the British Armies in France (Provisional), (HMSO June 1917).):

  • The Army Infantry School, training Company Commanders, Company Sergeant Majors and Sergeants.
  • The Army Scouting, Observation and Sniping School training officers intended to become Brigade or Battalion Intelligence Officers.
  • The Army Artillery School training Artillery Officers.
  • Corps Infantry School training Platoon Commanders and Platoon Sergeants.

The success of the awareness training is evident in an anecdote provided by a British company commander.  In 1917 C. J. Lambert with his Company of Royal Scots were occupying a sector of trenches near the Sencee River.  Their lives were being made miserable by a German Mortar which defied all attempts to pinpoint its location using the routine aerial photographs available as it was too well hidden.  In a further attempt to locate the mortar Lambert requested a dawn photograph in the hope that any tracks made by the mortar crew in the grass moistened by the early morning dew would reveal the mortars precise location.  In his own words Lambert describes the result:

‘In due course I was handed a composite photograph which told me everything I wanted to know.  It was a poor day for the trench mortar crew, . . . for the mortar ceased to trouble us following a call to our supporting artillery.’.  Medmenham Collection DFG 3410, Letter Lambert to Babingdon-Smith, 23 Dec 1957.

A key success that justified the organisational changes and the efforts being put into photographic interpretation training came during Third Ypres.  Haig in his diary entry for the 28 August 1917 recorded:

‘Trenchard reported on the work of the Flying Corps.  Our photographs now show distinctly the ‘shell holes’ which the Enemy has formed turned into a position.  The paths made by men walking in rear of those occupied, first caught our attention.  After a most careful examination of the photo, it would seem that system of defence was exactly on the lines directed in General Sixt von Armin’s pamphlet on ‘The Construction of Defensive Positions’ . . .’.  Gary Sheffield and John Bourne eds, Douglas Haig War Diaries and Letters1914-1918, (London, Phoenix, 2006) p. 320.

The II ANZAC Corps INTSUMS had begun to highlight the use of shell holes in late July:

‘. . . tracks lead to the river bank just north of the village, C 11 a 55.50 opposite the farms on the western bank; these run to shell holes or places where machine guns could be fired from (42B 1693).’  Australian War Memorial, II ANZAC INTELLIGENCE SUMMARY to 6 p.m. 23rd July 1917, AWM4/1/33/15 Part 2.

Following this discovery of what was the German defence-in-depth system the weight of British artillery barrages was switched onto the shell holes.  This change increased German casualties and dislocated their defensive system.

By the end of 1917 personnel with a remit to carry out photographic interpretation were located on the Intelligence Staff at Infantry Brigade and Battalion level.  The Brigade and Battalion Intelligence officers would have attended the ‘The Army Scouting, Observation and Sniping School’ whilst the support staff were trained at Division or Corps level by an aerial photograph expert.  During early 1918 Hughes (BIO 53 Squadron) conducted a number of these training sessions:

‘Thursday 17 January 1918 - I went to Corps to give my famous lantern lecture to a new group of would be Intelligence Officers from the trenches.  Hughes, ‘Diary’ of T McK Hughes.

The BEF of 1918 had succeeded in placing photographic interpretation personnel, trained to the appropriate standard, in intelligence sections at all levels.

Next: Part 18 ‘The Uses for Aerial Photography