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
British home army in the First World War the authorities with antipathy and censure, but it was formally recognised in 1916 as an official military auxiliary and incorporated, as the Volunteer Force, into the anti-invasion plans. A shortage of manpower at the end of 1917 resulted in further significant reductions in the home army. Four of its eight divisions were disbanded, and the partially-trained 19-year-olds in the remainder were replaced with raw 18-year-old recruits. The problem was exacerbated by the heavy losses suffered as a result of the German Spring Offensive in March 1918. The home army was stripped of all available personnel, leaving its ranks populated by