Poison gas was one of the most fearful weapons of its day and added a terrifying new dimension to modern warfare. In 1915, the only item a soldier had to protect himself from the harmful effects of gas was a shell dressing, soaked in his own urine and then tied around his face. By 1918, the British Army had developed a range of innovative protection methods that heralded the birth of the modern day military respirator. Throughout both World...