In 1915 the germans, not far ahead of the french and english, became the first people to unleash a form of chemical warfare, with the gassing of french troops. This first batch of gas was mainly a nuisance and scare tactic, because it only injured some people and wasn�t deadly. Later on both sides started using deadly gasses that were potent through the respiratory system and later through the skin. The gas was not the only thing that changed over time, the means of deploying the gas changed over time as well. At first gas was dispersed from an ordinary artillery shell, a canister was used after that but was stopped when the gas came back over the lines to kill the gassers. They then went back to using artillery shells with projectors, that made it more accurate.
