Poison gas was worse than than the other weapons of World War I because of its psychological impact and adverse effects on soldiers' morale. Stealth poison gas was insidious. The poison gases employed during World War I included chlorine gas, phosgene, and mustard gas. Although chemical weapons have a long and infamous history, the scale of their use in World War I was unprecedented.
Germany expected World War I to be a quick war. However, the war quickly became a stalemate as both sides settled down for prolonged trench warfare. German officers were not enthusiastic about chemical warfare at first, but they became increasingly desperate for a way to break the deadlock. Although Germany had signed international agreements banning the use of poison weapons, the desperation of German officers was the key to the deployment of poison gas.
Fritz Haber, a German Jew, was a capable scientist who wanted to demonstrate his patriotism by helping his country win the war. His wife, a chemist, believed science should be used for the betterment of mankind. In spite of her reservations, Fritz threw himself into his work. A lab accident, which killed his wife's friend, did not stop Fritz. After Fritz's poison gas was first used in battle, his wife killed herself with her husband's pistol.
In April 1915, the Germans used chlorine gas against unprepared Allied troops on the Western Front. German officers had not expected such powerful results, so they did not have enough troops to exploit their initial success.
Britain was surprised by the poison gas, but it quickly took countermeasures. Both sides issued gas masks. Poison gas, as terrifying as it was to World War I soldiers, did not change the outcome of the war.