A message dog leaping over a French soldier in a trench, 1916 (c)

Photograph, World War One, Western Front (1914-1918), 1916 (c).

Armies used dogs in various capacities. They were trained to carry messages and medical supplies, act as sentries and scouts, and were used in mine detection and seeking out casualties. The threat of snipers made it hard for people to carry messages over long distances. Dogs presented a smaller target and were able to travel faster than human messengers. Messages were carried in a tin slung around the dogs' necks.

From a collection of 164 official photographs.