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War of movement on the Western Front came to an end in October 1914. Between then and July 1918, the opposing armies occupied a system of trenches that ran from the North Sea coast to the Swiss border. The trench systems and the artillery and other positions behind them became the focus of intensive observation; they were examined, analysed and sometimes modelled in detail before each raid or general attack. Details of the enemy's positions came from observation from the air (by balloon or aeroplane) and from the front-line troops who had raided or taken prisoners. A sophisticated and thorough mapping of the enemy's trench systems grew up; hundreds of thousands of prints of trench maps were issued. However, like most military things they had a special jargon all of their own, and to the uninformed a Great War trench map is not an easy thing to intepret. This page will help. The trench maps of the Western Front compiled by the British Army during the Great War adopted the following system:
The area shown on each map was subdivided into a series of large rectangles, each identified by a capital letter of the alphabet. These rectangles were in turn subdivided into smaller squares numbered 1,2,3 … and in the larger ones up to 36. These squares covered a ground area of 1000 by 1000 yards. So for example, one of these 1000 by 1000 squares would be identified as S6 or T1 or B14. Each of these numbered squares is further divided into a two by two matrix of four squares, each measuring 500 by 500 yards. These were lettered in lower case a,b,c and d. a is top-left, b is top-right, c lower-left and d lower-right. So the reference for one of these 500 yard squares would be for example S6a, or T1b or B14d. Usually, especially for artillery purposes, much greater accuracy was called for. To achieve this, each of the 500 yard squares was considered to be subdivided into a ten by ten matrix of 50 by 50 yard squares. A specific point could then be identified by counting along the x-axis (West to East) in 50 yard segments, and then up the y-axis (South to North). So our example references could give S6a.4.3, or T1b.6.9 or B14d.1.2. To give an even more precise reference, imagine the 50 yard square was divided not into a ten by ten grid, but a hundred by hundred one. Each square in this grid would measure 5 yards square - about the size of a machine gun pit or a small blockhouse. Our example references could be S6a.42.38 or T1b.60.99 or B14d. 11.25. Bear in mind that each single trench map has say 40 or 50 of the numbered 1000 yard squares on it, so the numbers 1,2…36 may appear more than once. If there is any confusion, look out for the capital letter of the larger squares to which they belong. Today,
an original trench map is a sought-after and valuable object, although
the excellent CD ROM collection produced by Naval & Military
Press has made them more accessible. The National Archives has
a collection of maps too. They are a superb source of information
and provide a valuable if not essential insight to anyone planning
a visit to the battelfields. |
