Chemical weapons in World War I volatile oily liquid. It was introduced as a vesicant by Germany in July 1917 prior to the Third Battle of Ypres. The Germans marked their shells yellow for mustard gas and green for chlorine and phosgene; hence they called the new gas "Yellow Cross". It was known to the British as "HS" ("Hun Stuff"), and the French called it "Yperite" (named after Ypres). Mustard gas is not an effective killing agent (though in high enough doses it is fatal) but can be used to harass and disable the enemy and pollute the battlefield. Delivered in artillery shells, mustard gas was
German Army (German Empire) German Army (German Empire) The Imperial German Army () was the name given to the combined land and air forces of the German Empire (excluding the ' maritime aviation formations of the Imperial German Navy). The term ' is also used for the modern German Army, the land component of the ". The German Army was formed after the unification of Germany under Prussian leadership in 1871 and dissolved in 1919, after the defeat of the German Empire in World War I. The states that made up the German Empire contributed their armies; within the German Confederation, formed after the