British soldiers eating in a trench, 1917 (c).

Trenches were not dug randomly, but were part of a complex design. Each of the front line trenches was backed-up by second and third lines: ‘support’ and ‘reserve’ trenches. Communication trenches linked them all together. Soldiers did not spend their whole time in the front line. Whilst one unit was at the front others would be in support in case of attack, or out of the line entirely, resting and training in the rear areas. From a collection of 164 British, French and Belgian official photographs, World War One (1914-1918).