One of the most dangerous jobs undertaken by the engineers of the British and Commonwealth armies during the Great War was tunnelling beneath the enemy’s fortified positions to place an explosive mine.
Engineers lived with the constant risk of suffocation due to noxious gas or lack of oxygen. An essential part of any team of engineer tunnellers were the gas rescue men. Equipped with self-contained breathing apparatus, they would venture into collapsed mineshafts or dark, airless tunnels in a race against time with the hope of rescuing trapped mates. The gas rescue man wears his breathing apparatus, known by its trade name ‘Proto’, and between his legs he supports cages for birds and small animals whose sensitivity to oxygen levels served as an early warning of danger in the tunnels.