J. P. Cole, Military Instructors Manual
“ Troops in a trench should crouch down in the shadowy side and remain motionless. Faces should never be turned up, as the high lights on cheek-bones and foreheads then show up distinctly. Bright metal on arms, equipment and headgear must be kept covered. Artillery wagon-trains, etc., should if possible be halted promptly on warning. When halted, their neutral coloring protects them. Trenches are best concealed: By avoiding, in construction, a too regular outline, and following as far as possible the contours of the ground. By coloring the parapet and parados to match the ground. ”
