One of the most effective weapons used in WWI was chemical gasses which included chlorine gas, mustard gas, phosgene gas, and tear gas. Chemical gas often came in the form of bombs. Poison One of the most effective weapons used in WWI was chemical gasses which included chlorine gas, mustard gas, phosgene gas, and tear gas. Chemical gas often came in the form of bombs. Poison gas was invented by Fritz Haber, chlorine gas being the first example. The goal was to create a poisonous weapon powerful enough to harm and kill a soldier. It was first used by the Germans on April 22nd, 1915 against the French. More than 150 tons of chlorine gas was used against the French at Ypres, Belgium and was a very successful attack for the Germans. Chemical gases lead to approximately 1,240,000 casualties and 91,000 fatalities to both sides. The attacks of chemical gas were prevented by the creation of gas masks, the masks filters chemicals in the air for every breath. When a full-face mask is in use it’s important to have a rubber hood over the head to create a tight bond with the face, if not put on correctly gas will go through the crevices of the mask. Chemical gas effectively killed, enemies lead to many painful deaths, deformations. Chlorine gas was the first gas used and caused violent coughs, burned eyes, and lungs. Phosgene, an odorless gas caused more inhaling and had delayed effects causing a difficulty in breathing and was the deadliest of all the gases. While mustard gas was also odorless but contaminated soils and caused internal and external blisters on the body. The drawbacks of using chemical gas are that it affects everyone in the surroundings whether it be enemies, allies, soldiers or civilians and can spread quickly throughout the air. Soldiers often suffered many days before dying. Chemical gases were used in every war and are still in use today most common in mustard and tear gas.