This excerpt from a training manual explains how to camouflage a sniper's observation post and periscope in the trenches. Snipers generally acted alone or in pairs and watched patiently for hours for a target. Snipers did not have to perform the same trench duties as other infantry soldiers.
Canadian Handbook for Scouts, Observers and Snipers, p. 120-121
Hartland-Molson Library Collection
REF TECH U 220 C2 C3 1918