mustard gas

Chemical weapon, developed by the Germans in World War I and first used on 12 July 1917. A vesicant and systemic poison, it attacks the lungs when inhaled, while the vapour attacks the eyes, causing blindness, and in liquid form causes suppurating blisters on the skin.

Its early use was highly successful as its full effect only became apparent some hours after an attack. During the first three weeks of mustard gas attacks by the Germans, 14,276 troops suffering cases of gas poisoning were admitted to British military hospitals and about 500 men died.