MAPS
Set out below are links to original GSGS maps of the time, which can be used in conjunction with the map references given in the war diaries to pinpoint original locations on the ground. The list is not exhaustive but the main areas are covered, particularly in Holland, and further maps will be added as and when they are identified. The maps are mostly held by the British Library, McMaster University in Canada and the Library of Congress in the US.
Other websites providing original maps include:
National Library of Scotland: http://geo.nls.uk/maps/belgium/gsgs4040/googlemaps.html
Locations can be transposed onto modern-day maps (Google Maps/Earth, for instance) with a reasonable degree of accuracy by calculating the positions relative to salient features that are unlikely to have changed a great deal since the war (such as old roads, rivers, canals, churches, etc). Instructions for plotting 4, 6 and 8-figure grid references can be found below.
GSGS map references in the War Diaries
In the diaries, there are two main types of map reference used to identify locations with a greater or lesser degree of accuracy:
1. 4-figure map references, which indicate a 1km x 1km square on the map;
2. 6-figure map references, which indicate a 100m x 100m square on the map.
Where greater precision is required, as, for instance, when identifying the location of a temporary grave or field burial site, 8-figure or 10-figure map references, which indicate respectively a 10m x 10m square or 1m x 1m square on the map, are also occasionally used.
Four-figure map references
Map references always give the eastings (the 2-figure numbers along the top of the map) first and then the northings (the 2-figure numbers up the side), just like coordinates on a graph, where the x coordinate is given first followed by the y coordinate.
For example, on the map below, the town of Gheel in Belgium generally appears with a map reference of 0888, which is located in the square to the right (east) of the 08 easting (the blue figures running left to right in the middle of the map) and above (to the north of) the 88 northing (the blue figures running vertically up the right side of the map).
Six-figure map references
Six-figure map references presuppose the 4-figure reference square to be further divided up into a 10 x 10 grid.
On the above map, the church in the village of Elsum just to the west of Gheel would have a 6-figure map reference in the region of 071886, since it lies roughly 1/10 of the square to the right of easting 07 and 6/10 of the square up from northing 88.
Likewise, an example of an 8-figure reference might be a more accurate location for the same church at 07058860 with the 4th and 8th figures denoting the number of tenths of the 10 x 10 grid inside the 100m x 100m square of the 6-figure reference.