A soldier from 2/2nd Battalion The Royal Fusiliers using a trench periscope, 1915

Photograph, World War One, Gallipoli (1915).

Periscopes provided a less dangerous way of observing the Turks from the trenches. In its simplest form, a periscope could be just a stick with two angled pieces of mirror at the top and bottom.

From an album of 64 photographs compiled by Sgt A J Favell, Royal Fusiliers, Gallipoli, Egypt and Malta, World War One, 1915-1916.