During World War II in 1943 as allied armies were gaining a foothold in Italy, the Southern Italian town of Bari was a major port to supply the growing armies.
On December 2nd, 105 German bombers attacked the port catching the allies by complete surprise. 28 allied ships were sunk. One of them, the John Harvey, had a secret cargo of 2000 mustard gas bombs. They were there for retaliation in event of a German chemical warfare attack.
The destruction of the John Harvey released nitrogen mustard into the air and water. 628 service personnel and civilians developed mustard poisoning. 83 ultimately died and many underwent autopsy. At autopsy, changes to the bone marrow and destruction of lymph tissue were noted. This observation led to experiments and the ultimate development of the first chemotherapy, Mustine; and the class of chemotherapy called alkylating agents; many of which are still used today.