|Fritz Haber, 1919. From Wikipedia.|
In my own view, I mainly remember him for his development of poison gas that was used on the battlefields of World War I under his direction. He's thus known as the "father of chemical warfare." Historian Fritz Stern in Einstein's German World, described Haber's participation in World War I as follows:
"During and after the war, Haber tried to explain his work in developing a weapon that outraged many people -- in Germany, but especially abroad. The Hague Conventions of 1899 and 1907 had prohibited the use of poisoned weapons. Haber believed that the use of gas would bring the war to a quick conclusion; he argued that the gas, which immobilized but usually did not kill, was a more humane weapon than the artillery bombardments that had become routine; he pointed out that the Allies had their own plans for introducing gas warfare, and Germany had merely anticipated them. It would appear that neither Haber nor those closest to him, like Willstätter, worried about the legal and moral issues involved, such was the brutish atmosphere of war. Gas warfare did not prove decisive, though its horror -- the terrifying choking, the blinding, the deaths, the experience even for survivors of a living death -- has become an inextinguishable part of our collective memory, an early instance of science put to satanic service. (p. 120)The industrial work continued after World War I. Haber was head of the prestigious Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry. Although the Nazis would have at least temporarily allowed him to stay in his position despite being Jewish (though a convert to Christianity like many ambitious German scientists), he resigned when it became obvious that he would be required to fire all his Jewish subordinates. He left Germany, but died soon afterwards.
There's much more to say about Haber, his life, and his work. I only mention that one of his commercially-produced types of poison gas was Zyklon B, used in the gas chambers.