Apparently Hitler's generals urged him to use chemical weapons against Allied armies but he demurred. I guess this is ancient history, but I don't remember knowing it before. Or if I heard it before, I heard it always explained as pure pragmatism--that is, that Hitler refrained only because he knew the Allies had gas too (and presumably he knew also from Dresden that we weren't squeamish about wiping out whole cities worth of civilians). But just now on NPR I heard a guy interpret Hitler's hesitation as personal, and probably to do with Hitler's own exposure to gas in WWI. I could believe that. He was a vegetarian and conservationist too. Compartmentalization is a wonderful thing.