Trench map
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A Trench map shows the trenches of the Great War, 1914-1918. Whilst all of the belligerents made or used maps of the trenches, this article refers mainly to those made by the British Army.
The term Trench Map is used as the title of maps that detailed the trenches of the Western Front and produced by the GSGS, the Geographical Section, General Staff, which was part of the War Office.
For much of the Great War, trench warfare was almost static, giving rise to the need for detailed large scale maps for both attack and defence. Initially, British trench maps showed the German trench systems in detail but only the British Front line. Later in the war, more and more of the British trenches were shown. The only maps that showed full detail of both sides were the secret editions, usually marked "Not to be taken beyond Brigade HQ" for fear of them falling into enemy hands.
The majority of trench maps were to a scale of 1:10,000 or 1:20,000 but maps of 1:40,000, 1:80,000 and smaller scales were printed. Many of the 1:40,000 maps show trenches but were of little use to front line troops. The infantry preferred 1:10,000 and the artillery, mainly 1:20,000 but 1:40,000 were used by the heavy artillery. In the Report on Survey on the Western Front 1914-1918, published in 1920, Colonel E.M. Jack wrote "The 1:20,000 was the map commonly used by the Artillery, and as trenches could be shown on it in sufficient detail to be of use to the infantry it was the most useful scale of all, and the one that could least easily be dispensed with." Colonel Jack was a key figure in Great War cartography.
At the start of the war there were no trench maps, trench warfare had not developed nor had the technology to create them at the speed required. The British Army went to war with maps more suited to a "war of movement", i.e. small scale of a quality just about adequate for marching. Once the line had become static after the Battle of the Aisne and the Race for the Sea, the need for accurate detailed maps became urgent.
The earliest trench maps date from 1915 and were made from enlargements of French and Belgian maps of variable quality. Some re-surveying of the front was carried out when it was found that such enlargements were not sufficiently accurate. Accuracy was paramount to the artillery, especially later in the war when techniques were developed to "shoot from the map".
A trench map consists of a base map that shows roads, towns, rivers, forests etc., over printed with trenches, red for German, blue for British. Early in 1918 these colours were reversed to come into line with French practice. To add to the confusion, some trench maps were printed with all the trenches the same colour. A base map usually had an edition number followed by a letter, so a map marked 6C had an edition 6 base map and the trench over print of edition C. This system was not strictly adhered to, sometimes two maps with the same number and letter can be found but with different detail and dates. On many of the maps, it states "Trenches corrected to" followed by either a single date or a separate date for British and German trenches.
The trench maps were updated from aerial photographs and intelligence reports although sometimes captured German maps were used as a source of detail. The use of aerial photography in cartography developed to an enormous degree during the Great War. Before 1914, experiments had been made and papers written on the subject but little was available to the Army for actual use. By the end of the war, it was possible to produce accurate photographs and to transcribe detail to accurate maps as well as the assessment of height of the land forms.
Most of the maps were printed in England or well behind the lines as the printing presses were not easy to move at short notice should an attack by the Germans be successful. Some small sheets were made nearer the front by other techniques but the regular series trench maps were printed using lithography on large presses by very skilled printers. Some use was made of zinc in the lithographic process but many were printed using lithographic stone, the origin of the term lithography.
An estimated 32 million maps were printed in the Great War but most have been destroyed. Many are in private hands but important collections are available for public viewing at the Imperial War Museum in London and TNA, the National Archive at Kew. Digital versions are also becoming available as interest in the Great War increases.
References
Textbook of Topographical and Geographical Surveying by Colonel C.F Close, C.M.G, R.E. Director General of the Ordnance Survey.
Report on Survey on the Western front, 1914-1918, Published in 1920, HMSO. Written by Colonel E.M. Jack
Artillery's Astrologers, A History of British Survey and Mapping on the Western Front 1914-1918 by Peter Chasseaud, ISBN 978-0-9512080-2-1
Trench Maps - A Collectors Guide (1986) - by Peter Chasseaud, ISBN 978-0-9512080-0-7 (Out of print)
Topography of Armageddon - A British Trench Map Atlas of the Western Front (1991, reprinted 1998) - by Peter Chasseaud, ISBN 978-0-9512080-1-4.
