Chemical weapons were first used on a major scale by the Germans in 1915 to try and break the deadlock on the Western Front. Early gas masks were simply cotton pads soaked in chemicals or poorly ventilated hoods with eyepieces that fogged up and cracked. But as chemical weapons developed, so did protective equipment. The 'tube' helmet pictured here has glass eyepieces and a rubber tube through which a soldier could breathe. It was infused with chemicals to counter phosgene gas, one of the most dangerous poison gases. However, the mask could be uncomfortable to wear. One of the chemicals caused eye irritation and skin blisters. The 'tube' helmet was eventually replaced by the Small Box Respirator mask, which was the most effective of the wartime gas masks. On the Western Front, death rates from gas were relatively low - about 3 per cent - but the physical effects were agonising and it remained a pervasive psychological weapon.