It evolved from the use of poison gas during both the world wars. Gas warfare killed 91,000 soldiers, and invalided another 1.25 million, in World War I, including one sulphur mustard attack in 1917, which claimed 14,278 casualties in very short time.
And so the use of sulphur mustard continued, by the Italians against the Ethiopians in 1936, and in an accidental explosion at Bari during World War II, which consigned a thousand soldiers to a slow and agonising death.
After the Bari attack, doctors noticed that the victims' white blood cell count dropped alarmingly, and wondered whether nitrogen mustard might have some medical use.
The rest, as they say, is history.
(Source: Journal of the American Medical Association, 2006; 296: 1518-20).
E-news broadcast 5 October 2006 No.298 [Subscribe]