Germany was the first state to develop the technology of gas mass-production. Mustard gas was prepared by combining sulfur dichloride with ethylene.
The effects on the human body were atrocious. A British nurse commented:
"They cannot be bandaged or touched. We cover them with a tent of propped-up sheets. Gas burns must be agonising because usually the other cases do not complain, even with the worst wounds, but gas cases are invariably beyond endurance and they cannot help crying out."
The Geneva Protocol of 1925 prohibited chemical warfare, including the use of mustard gas, although it was occasionally used by the Germans in World War II.