When the German army unleashed their secret weapon upon Allied soldiers in April 1915, none were prepared. A thick yellow cloud of poisonous gas advanced across No Man’s Land and within ten minutes thousands had died from asphyxia or been permanently blinded.
In the weeks that followed, soldiers were issued with cotton mouth pads soaked in urine, as it had been discovered that ammonia helped to neutralize chlorine. These were quickly replaced by the Black Veil respirator invented by John Scott Haldane, which was treated with a far less-stomach churning sodium-based solution.
