How to find a point on an early trench map

The early Great War maps used the system of squaring below. This is found on some 1914 and early 1915 maps, notably the 1:40,000 series.

The map is divided into large squares, lettered "A", "B", "C", "D", etc., the sides of which are 5,000 yards in length.

The large squares are divided into 25 smaller squares, numbered 1 to 25, the sides of which are 1,000 in length.

The areas 6, 7, 8, 9, 10, in squares CC, DD, EE, FF, GG, HH, JJ, are rectangles of 1,000 yards by 830 yards.

The minor squares and rectangles are to be considered as lettered "a", "b", "c", "d," but the letters are only printed in one small square to avoid confusing the map.

A point can thus be described as lying in square A.2.c, D.5.a, etc.

If the position of a point can be identified more closely, the further description N, S, E, or W may be added.

If only the description of the small squares is given, e.g., A.2, the position indicated will be taken to be the centre of A.2. Similarly, A.2.d. will be taken as meaning the centre of the minor square A.2.d. unless a further description N., S., etc., is added.

The description A.2.c.d. can be used if uncertainty exists as the whether "c" or "d" is the correct minor square.

Most maps of the Great War did not use this system. When it was superceded, for a while maps were marked "Revised System of Squaring". To find a point on these maps, see the main article on How to find a point on a trench map.