It was the Germans in WW1 who first realised how chemical weapons could be used to break through a trench stalemate at Ypres in April 1915. It was British gas masks then which nullified this weapon.

G is for Gas. videoG is for Gas School pupils handle a British gas mask from WW1. Newsreels of the period show soldiers using gas masks in training and at the front.

Around 650,000 Canadian soldiers fought in WW1. In the east ... Army soldiers died during the battle. A British Vickers machine gun crew wearing gas masks near Ovillers during the Battle of ...