Chemical warefare in the First World War

In the First World War poison gas was used by both sides. The French were the first to use gas, but they only used tear gas which was not poisonous. The Germans soon after started using gas which was poisonous. The use of poison gas was a war crime for the use of poison, or poisoned weapons was prohibited by the 1907 Hague convention on land warfare.

British gas victims

 A couple types of gas employed in the war were chlorine and mustard gas. Chlorine gas was invisible and attacked the eyes, nose, and lungs the effects of which could be avoided by wearing a gas mask. Mustard gas not only attacked the nose, eyes, and lungs, but the skin. While chlorine gas disperses rather rapidly after the initial attack, mustard gas lingers for hours and maybe even days. The over all effectiveness of gas in the First World War was rather small. Casualties due to it totaled only about four percent.