Soldier ready to ring the bell to give warning to a gas attack. In the Western Front they took gas attacks as "all in the days work", every soldier carried his gas mask on him; adequate medical antidotes are at hand; while, to ensure due warning being given of the letting off a gas-cloud, the greenish-yellow vapour is seen rising above the enemy's front trenches, alarm-bells are clanged which a sentry of the South African Contingent pulling the clapper to give warning.