<P> Chemical weapons were first used systematically in this war . Chemical weapons in World War I included phosgene, tear gas, chlorarsines and mustard gas . A secret report by Lt Colonel C.G. Douglas, on the physiological effects of chemical weapons, stated that "the particular value of the poison (mustard gas) is to be found in its remarkable casualty producing power as opposed to its killing power". The report said that 1% of British troops died due to chemical weapons, while an estimated 181,000 soldiers were victims of gas casualties . Chlorine gas was first used by Germany, in the Second Battle of Ypres in 1915, with great effect . </P> <P> Chemical weapons were easily attained, and cheap . Gas was especially effective against troops in trenches and bunkers that protected them from other weapons . Studies show that over 1,300,000 people were exposed and intoxicated by gas during the First World War, and 90,000 were killed due to gasses . </P> <P> Chemical weapons attacked an individual's respiratory system . The concept of choking easily caused fear in soldiers and the resulting terror affected them psychologically . Because there was such a great fear of chemical weapons amongst the soldiers it wasn't uncommon that a soldier would panic and misinterpret symptoms of the common cold as being affected by a poisonous gas . </P> <P> Aviation in World War I started with primitive aircraft, primitively used . Technological progress was swift, leading to ground attack, tactical bombing, and highly publicized, deadly dogfights among aircraft equipped with forward - firing, synchronized machine guns from July 1915 onwards . However, these uses made a lesser impact on the war than more mundane roles in intelligence, sea patrol and especially artillery spotting . Antiaircraft warfare also had its beginnings in this war . </P>

What were the weapons used in world war 1