But it also led to an army doctors serendipitous discovery of a new treatment for cancer.
Allied ships burn during the German attack on Bari.
Mustard gas was used extensively by the Germans during the First World War.
It was a feared weapon that caused sever skin oedema and ulceration, blindness, suffocation and vomiting.
Mustard gas caused internal and external bleeding and attacked the bronchial tubes, stripping off the mucous membrane.
This was extremely painful.
Fatally injured victims sometimes took four or five weeks to die of mustard gas exposure.
The use of this gas and other chemical weapons in war was banned by the Geneva Protocol of 1925.
However, there was no ban on their manufacture or transport.
On 26 November, the John Harvey sailed through the Strait of Otranto to arrive at Bari.
On December 2, 1943, the Germans launched a surprise attack.
John Harvey was struck and destroyed in a huge explosion.
Its deadly cargo of liquid mustard spilled into the water mixing with oil from the sunken ships.
Some mustard evaporated and mingled with the clouds of smoke and flame.
The doctors suspected some form of chemical irritant but were unsure what it was.
Unidentified Canadian soldier with burns due to mustard gas in 1917.
Then suddenly, patients who were in relatively good condition started dying.
These mysterious deaths left the doctors baffled.
Lieutenant Colonel Alexander immediately recognized the symptoms as the result of mustard gas poisoning.
Alexanders report was immediately classified, and all mention of mustard gas was stricken from the official record.
The deaths were attributed to simply burns due to enemy action.
However, the presence of multiple witnesses forced the United States to eventually admit the presence of the chemical.
In all there were 628 known casualties, including 86 deaths, but there were probably many more.
The cloud of vaporized mustard gas had drifted across the town affecting and killing many more civilians.
These deaths were never recorded.
In the midst of the disaster, Lieutenant Colonel Alexander made an interesting discovery.
While studying tissue samples of autopsied victims, Alexander discovered that mustard gas kills white blood cells.
A preliminary research conducted in 1935 showed that mustard gas inhibits growth of tumors in mice.
Their improvement, although temporary, was remarkable.
The University of Chicago conducted similar clinical trials using a different agent.
But wartime secrecy prevented any of this ground-breaking work on chemotherapy from being published.
Eventually, the first chemotherapy drug named Chlormethine was developed.
