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
Halberstadt CL.II Halberstadt CL.II The Halberstadt CL.II was a German two-seat escort fighter/ground attack aircraft of World War I. It served in large numbers with the German "Luftstreitkräfte" (Imperial German Army Air Service) in 1917-18. Early in 1917, "Idflieg", the German Army Inspectorate of Flying Troops, developed a requirement for a new type of two-seat aircraft, smaller than the existing C-type aircraft. This type, to be known as CL-type (Light C type) aircraft, were to be used to equip "Schutzstaffeln" (Protection flights) to escort reconnaissance aircraft. To meet this requirement, Halberstadt developed an aircraft based on its earlier, unsuccessful Halberstadt D.IV single-seat