The new trigonometrical surveys were made in conjunction with de Larminat’s surveys of the French sector of Helles and the Asiatic Shore (see below) which resulted in an Anglo-French 1:20,000 map. They included the islands off the Peninsula and southwards to Tenedos, and were also of great value to the Navy, which supplied the bulk of heavy artillery support. The triangulation was later linked via Imbros to the Anzac and Suvla sector. The progress of this Anglo-French survey, and its related mapping, was slow, despite the fact that survey photographs were being taken from the air in early August. On 5 November VIII Corps (Helles) issued the following information: ‘An accurate survey, showing both our own and the Turkish trenches, on a scale of 1/10,000, is in course of preparation by GHQ and, when ready, will supersede the present 1/20,000 map and the 1/6,000 trench diagram.’30
The Survey Section from Gallipoli was, following the evacuation, shipped to Salonika and ultimately developed into the Field Survey Company, British Salonika Force (later 8th Field Survey Company) under Lt-Col. Henry Wood RE who had previously commanded 1st Field Survey Company in France. It was Wood who would return to Gallipoli after the Armistice to check the accuracy of the Turkish maps. Nugent was awarded the DSO for his survey work on the Peninsula; Newcombe was also decorated, not for survey work but for rescuing Anzac tunnellers from a gas-filled mine.
VIII Corps mapping in the Helles sector
Weeks before Nugent set to work, in fact only ten days after the landings of 25 April, Commander Henry Douglas RN and Lieutenant Nicholas (Maps Officer, GHQ) went ashore to survey the topography of Helles and the Turkish defences, partly as a matter of historical record. The result was a 1:9,000 (4 inches to 1,000 yards) scale ‘Plan of S.W. end of Gallipoli Peninsula Showing Turkish Defences as existing 25 Apr. 1915’, dated 5 May 1915, augmented by a panoramic drawing entitled ‘General View of S.W. end of the Gallipoli peninsula before the landings.’ These were beautifully lithographed on one sheet in several colours by the Survey Department, Egypt.31
We see in Gallipoli in late May and early June the creation of an entirely new type of very large-scale (1:600) trench map, or ‘trench diagram’, necessitated by the fact that operations had, because of the firepower of modern weapons (mostly rifles and machine guns), immediately degenerated into trench warfare, as on the Western Front. They had to show as much topographical detail as possible in order to locate Turkish defences from air photos. A precisely similar procedure was begun at about this time in France.
For the Third Battle of Krithia early in June, the first such trench diagram was prepared by Captain Nugent, covering the area in front of Krithia, with the sea on the left, printed by the GHQ Printing Section at Imbros, and issued with VIII Corps Orders on 3 June. This was the first of a long series of such diagrams progressively improved and completely plotted from air photos, which were the equivalent of the ‘trench diagrams’ and later ‘trench maps’ in use on the Western Front. It was entitled ‘Diagram Showing Advanced Turkish Trenches & Communications’, and carried a note explaining that ‘The diagram is based on information available up to the afternoon of June 1st. Reliance however, must not be placed on the diagram showing every Turkish trench.’ The ‘Reference’ key showed British Trenches, Turkish Trenches, Communication Trenches, probable Turkish machine guns, Roads, Tracks, Watercourses and Wire entanglements. A further note stated that: ‘The relative positions of the trenches are correct within small areas, but the diagram should not be used to measure long distances or bearings.’32
Similar trench diagrams were issued dated 17 June, 22 June, 26 June, and at frequent intervals thereafter. While the first one (1 June) was lacking in detail, it did indicate roads, sunken roads, tracks, nullahs (watercourses), Gully Ravine, vineyards, orchards, olive groves, the village of Krithia, ruined houses, woods, hedges, areas of scrub, as well as the trenches and other tactical detail indicated in the Reference. As the series developed, successive editions showed ever more and more accurate planimetric detail, such as field boundaries, and also gave a better portrayal of the relief aspects of the terrain through more accurate depiction of nullahs, cliffs and so forth. They were not, however, contoured.
We saw above that in July, in conjunction with the French, Dowson and Nugent started a trigonometrical framework, extending into enemy territory, for artillery work and as a control for air photos, and Dowson obtained a ‘Bahel’ restitution apparatus from Egypt.33 Most of this work was in connection with the Helles sector.
One map – ‘Map Showing British & French Trenches, Gallipoli Peninsula, Southern Zone 7th July 1915, Secret, 8th Army Corps’ – according to the Western Front surveyor F J Salmon, ‘was produced by the Engineer Unit of the Royal Naval Division and is merely a diagram, having been compiled from sketches, sextant and prismatic compass work’.34
The VIII Corps ‘Maps’ Officer on 25 August was Captain H M Chrystall.35 This may have been a local rank only, for a Lieutenant H M Chrystall RE served with 3rd and 5th Field Survey Companies RE in France as a Trig Officer in 1918.36 A secret lithographed foolscap VIII Corps ‘Trench Diagram of Left and Centre Sectors’ (6th Series, 5 November, scale 6 inches = 1 mile), showing detail in black and British trenches in red, was drafted at Royal Naval Division HQ by ‘J.H.L.’.37
The Anglo-French survey only slowly resulted in new mapping of the Helles sector. On 5 November Brig.-General Street of VIII Corps General Staff issued an ‘Instruction on maps and survey’ asking lower formations to produce 1:2,500 sketch maps which would be used to produce 1:5,000 Corps diagrams showing trenches and communications, and noting that an accurate 1:10,000 survey showing Allied and Turkish trenches was being prepared by GHQ. This would replace existing 1:20,000 maps and 1:6,000 trench diagrams, and in future all sketch plans should be at some denominator or multiple of this 1:10,000 scale.38
French maps and the Anglo-French survey
Despite the close pre-war relationship between the French Service Géographique de l’Armée and the Turkish survey department in Constantinople, the French were as cartographically ill-prepared as the British. The original map served out for the landings was, as we have seen, the British 1:40,000 based on an earlier one-inch map which was, in turn, based on the French Crimean War 1:50,000 survey.
The French Government agreed that their Army and Navy detachments serving at the Dardanelles should come under British command; the French military force was designated the Corps d’Expéditionnaire d’Orient (CEO), and when this departed from France on 2 March 1915, its Service topographique comprised only a Section de Topographie consisting of Captain de Larminat (Infantry) and his clerk, Corporal de Jerphanion. From this date up to the end of April, i.e. during the crossings and the landings (at Bizerta 6–10 March; Mudros 15–26 March; Alexandria 28 March–16 April), it was concerned with coordinating the information already received about the location of Turkish divisions, and showing these graphically on enemy-order-of-battle maps.
The French landed at Kum Kale on 25 April as a diversion, but immediately pulled out and took over the British right flank at Helles. On 2 May de Larminat installed himself with d’Amade’s French Force HQ in the ditch of the ruins of the ‘Old Castle’ at Sedd-el-Bahr. He used the Crimean War 1:50,000 map reproduced by the Service Géographique de l’Armée in Paris, and also the British 1:40,000 map derived from it, ‘both of which needed serious alterations to meet the requirements of trench warfare’. As soon as British 1:20,000 and 1:10,000 sheets, based on captured Turkish maps, became available, they were supplied to the French Section.
The first French operations maps were crudely reproduced on a composition duplicator, protected only by a tarpaulin stretched against the wind and the dust, or in a tent. These were merely 1:5,000 and 1:10,000 sketch maps, enlarged from the 1:40,000 and 1:50,000 maps, showing the situation and new tactical information – including French positions, trenches, and enemy batteries. Copies of these were sent to Hamilton’s GHQ at Mudros.39
Captain Cesari’s squadron, l’Escadrille 98
T, arrived at the Dardanelles early in May, joining the RNAS at Tenedos. The first French air photos, taken about mid-May by Lieutenant Saint André, provided sufficient data for the reproduction of rough diagrams of the French and Turkish trenches. These were accurate enough in their detail, but like those of the British were not based on any triangulation network; this did not yet exist, as the Allies had not captured any Turkish trigonometrical data.
The inadequacy of the existing maps led to an expansion of the Section, and a shift of location into the Deuxième (Intelligence) Bureau’s HQ tents until better accommodation was found in June. The strength of the Section at the end of May was eight. Only de Larminat and de Jerphanion, his deputy, were trained topographers; three of the others were draughtsmen. On 1 July Captain Thomas (trig officer and topographer), Boudineau (topographical draughtsman) and Desoye (litho draughtsman) arrived from Paris. Thomas, a colonial artillery officer, was a geodetic survey expert and was responsible for most of the artillery survey and the creation of the new plan directeur, or artillery map. These three were followed by Sgt-Major (adjutant topographe du cadre du Service Géographique) Léopold Martin on 9 July; he was later promoted to sous-lieutenant. By 11 July some thirty unsquared ‘situation’ trench diagrams had been plotted and reproduced at scales varying from 1:2,500 to 1:20,000. The normal scale of issue totalled seventy-four copies, but this was sometimes exceeded.40
Towards the end of June, General Gouraud, who had taken over command from d’Amade and was concerned about Turkish artillery fire from the Asiatic Shore, ordered an artillery survey to be made so that these guns could be accurately located and dealt with. This solution was the same as that which had to be applied on the Western and other fronts in 1914–15. Work therefore began on the trig survey which was to form the foundation of the Anglo-French 1:20,000 artillery map (and an excellent gridded plan directeur). De Larminat, who was promoted chef de bataillon (major) on 15 July, measured a base starting from the western end of Cape Tekke plateau, and built onto this, using a small theodolite and a steel surveyor’s tape, a triangulation of the French area, extending this to the limits of visibility. Conspicuous points were fixed by theodolite observations, and calculated in rectangular coordinates. He executed a network of nine trig stations covering the Allied tip of the Peninsula, and by 11 July had added seven more stations.
He later extended this network to include Rabbit Islands (a group of small islands between Tenedos and Cape Helles) and Tenedos, and from these southern stations intersected points on the Asiatic side of the Dardanelles. Meanwhile Thomas completed the network within the Peninsula, where some sixty trig stations were eventually established. The work was obstructed by the almost instantaneous disappearance of every trig signal they erected, as this small area – the French sector at Helles extended on a 1-km front to a depth of 3.5 km – was overcrowded with troops. Martin carried traverses from these stations to the French heavy batteries, the same technique used by the French on the Western Front.41
Integration with naval surveys
The triangulation proved extremely useful to the Army and Navy. By 11 July twenty-four points on the Asiatic Shore had been fixed, and by October, seventy-five. On Tenedos itself, seven points were fixed, and three on Rabbit Islands; these ten points were initially not as reliable as the others, being observed in bad weather conditions. Their purpose was to help French naval gunnery, and the gunnery officer of the Saint Louis expressed his appreciation. In October the triangulation was recomputed, the new values being based on later, more carefully observed rays.42
The British Fleet also used the French triangulation for its shooting, and Ramsey, de Robeck’s Flag Commander, informed de Larminat on 30 July that:
… we have been served by your triangulation for all our shooting from Rabbit Island, and I found it not only useful but much more accurate than our own. The French naval liaison officer has passed it to me, and I have since heard that the 14-inch guns of Roberts have been ranged onto a target with a sight elevation which, following your triangulation, had to be 14,025 metres and which the aeroplanes had ranged to 14,050 metres, a difference probably due to the wind. Our topographer on board Roberts has fixed himself according to your calculations, and he has already triangulated a portion of the coast around the Island of Mavro. We now have another 24cm [9.2-inch] monitor. Benefiting from your valuable work, they are also able to fire accurately by night as well as by day and I am confident that the result will contribute to making life very pleasant in the French camps as on the beaches.43
A British report on the spotting work of British seaplanes observing the fire of the monitor Roberts from 22 July stated that:
The range was first measured off geographically by a very careful triangulation and survey ranges reached 19,500 yards (10 nautical miles), probably the longest at which guns have been fired in naval warfare.44
The Turkish batteries on the Asiatic Shore opposite Helles were located with the help of a map based on an air-photo mosaic, made by Lt Saint André, fitted onto the observed points. This comprised some thirty same-scale, near-vertical photos. Batteries near fixed points were relatively easy to plot, ten such being fixed by 11 July. Around In Tepe, near Toptash Burnu on the Asiatic Shore, the density of fixed points and the large number of air photos on which these could be identified enabled a mean photo-scale to be established and new detail points on the photos to be plotted. Thus the original ‘high-order’ triangulation was progressively amplified, admittedly with ‘lower-order’ points, from the photo-restitution, and a dense ‘canevas de restitution’ was developed, again in a similar way to the Western Front.45 Farther to the west and south, where there were fewer fixed points, overlapping strips of photos between points were taken at the fixed scale of 1:6,000 (implying a constant altitude during the sortie). On these adjusted strips, grid cuts were plotted between the fixed points, and detail traced from the photos as described below.46
The lack of accurate maps of the Gallipoli Peninsula made the restitution of air photos very difficult, as the British also found. Various methods of graphic restitution, such as craticulage or faiscaux anharmoniques used on the Western Front, were unsatisfactory in Gallipoli because they depended on an existing reliable planimetric framework. Thomas developed a technique based on the points of the new triangulation. Starting with pairs of trig points on the 1:20,000 map which could also be identified on an air photo, he measured the distances along a line joining the two points to a grid line, and transferred these proportionately to a line joining the same points on the photo, thus plotting grid cuts and enabling the reconstruction of the map grid on the air photo. The photographic detail was next drawn onto the map relative to the grid. Not only topographical detail, but trenches and enemy batteries could be plotted in this way. Despite its approximate nature, the method was justified by its speed, by the fact that many near-vertical photos were available, by the relatively level ground, and by the lack of alternative methods.47
Vertical relief (ground-forms) was more difficult to depict accurately than planimetry because stereoscopic air-photogrammetric methods had not yet been developed, but the contours of captured Turkish maps were extremely useful. Otherwise, the usual practice was to interpolate form-lines using the network of points for which planimetric and height values had been obtained. Air photos were also studied to assist the contouring of dead ground. In the In Tepe area, air photos taken when the sun was low enabled shadows to be utilised to identify features of the terrain, identified by visual reconnaissance from the air, and their approximate three-dimensional forms to be reconstructed. This method was extended along the west coast past Besika Bay, amplified by data from drawn panoramas made from the islands.48
This triangulation enabled a new 1:20,000 map to be created, based on ground surveys at Helles, combined with the 1854 survey and air photos. This new map of the Allied zone extended a long way into enemy territory, and was lithographed in colour by the Survey of Egypt. A further 1:20,000 map of the Asiatic c
oast, covering about 150 square km from Erenkeui on the Asiatic Shore opposite Helles, past Kum Kale and Besika Bay to the coast abreast of Tenedos, was simpler than the one of the Peninsula and was entirely based on French air photos. It was fixed onto a triangulation and was printed on a small hand-press of the Deuxième Bureau (Intelligence). Detail was in black, and for this area hachuring was used rather than contouring, for which there was insufficient data, apart from captured Turkish maps, owing to a faulty theodolite incapable of taking vertical angles.
In October Thomas produced a provisional 1:10,000 gridded and 5-metre contoured plan directeur for the Helles sector showing Allied and Turkish trenches and Turkish batteries, almost indistinguishable from those in use on the Western Front. This was reproduced by the British GHQ Printing Section, and was also used by British units.49 Thomas interpolated contours as described above, also using the drainage pattern and other data derived from Turkish maps.
Following the formation of the French Salonika Army, Commandant de Larminat and Captain Thomas were both attached to the Armée d’Orient and left Sedd-el-Bahr for Salonika on 4 October. The Service (or Bureau) Topographique des Dardanelles was then directed up to the evacuation in December 1915 by de Jerphanion.50
The Anzac sector
Mapping the Anzac sector was extremely difficult because of the rugged, tangled terrain and limited perimeter; any attempt at forward mapping using normal ground survey techniques would be greeted with ferocious sniper and shrapnel fire. Even more than at Helles, therefore, captured Turkish maps were vitally important, and were first utilised by straight copying or enlarging, with transliterated place names. An unsquared black 1:10,000 contoured sheet was soon produced, entitled Map of Area occupied by Australian & N.Z. Army Corps, Enlarged from a Turkish map (Z.2021, one copy with MS trenches dated 15 June: British in red and Turkish in green51), followed by another (Z.2024A), still unsquared, with the same title and scale with brown contours at 40-foot (heavy at 200-foot) intervals, at least one copy of which had trenches in MS: British (i.e. Anzac) in red, and Turkish in green. The brown contour plate was registered with needles, as was standard army practice using hand-press stone-litho processes.52 A further black 1:10,000 map, Koja Chemen Tepe, covering the Chunuk Bair and Biyuk Anafarta area north-east of Anzac Cove, was clearly from a captured Turkish map, and was both contoured and squared (Squares 92, 93, 80, 81). Some zones on this map were hatched to show wooded areas.
Grasping Gallipoli Page 35