We examine the first "chemical war," The Great War, or World War I, and its aftermath, and what made it so. Chlorine gas, phosgene gas, mustard gas, and Lewisite were the products of this era. We also discuss the chemical and political career of Chaim Weizmann, the "father of industrial fermentation," and the checkered history of Fritz Haber. Two decades after the Great War, the Nazis invented nerve agents, and used a pesticide to exterminate millions of people.Support the show Support my podcast at https://www.patreon.com/thehistoryofchemistry Tell me how your life relates to chemistry! E-mail me at steve@historyofchem.com Get my book, O Mg! How Chemistry Came to Be, from World Scientific Publishing, https://www.worldscientific.com/worldscibooks/10.1142/12670#t=aboutBook