In 1914 a chemist called Fritz Haber offered his knowledge to the German Army. He soon began experimenting with chlorine gas to be used in trench warfare.

World War I was the first conflict to introduce chemical warfare on an international scale, and as a result, the gas mask became a regular tool for soldiers on the front lines. Chemical weapons ...

The First World War was the first-time poison gas was used on a large scale during war. The gas could affect someone in just a few minutes so protective masks were ... put into one of three ...