+Poison gas refers to toxic substances weaponized to incapacitate or kill. First used extensively in [World War I](/wiki/world_war_i), its deployment marked a horrific new era in [chemical warfare](/wiki/chemical_warfare), causing immense suffering.
+## See also
+- [Chemical Weapons](/wiki/chemical_weapons)
+- [Geneva Protocol](/wiki/geneva_protocol)
+- [Mustard Gas](/wiki/mustard_gas)
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