Mustard gas was one of a number of weaponised poison gases developed by Fritz Haber, a Professor at the prestigious University of Karlsruhe. Haber was a brilliant chemist, who invented a process for the industrial scale production of ammonia-based fertiliser. This brilliant discovery, known as the Haber process, played a huge role in avoiding worldwide famines and now feeds about a third of the world's population. It won him the Nobel Prize in Chemistry in 1918.
Two doctors at Yale University, Louis Goodman and Alfred Gilman, delved into the medical records of soldiers affected by mustard gas, and noticed that many of them had a surprisingly low number of immune cells in their blood – cells that, if mutated, can go on to develop into leukaemia and lymphoma.
Goodman and Gilman hypothesised that if mustard gas could destroy normal white blood cells, it seemed likely that it could also destroy cancerous ones.
After successful animal trials, Goodman and Gilman looked for a human volunteer with white blood cell cancer to test mustard gas as a cancer therapy. They found a patient with advanced lymphoma, known today only by his initials: J.D.
A massive tumour on J.D.'s jaw meant he couldn't swallow or sleep – he couldn't even fold his arms across his chest because the tumours in the lymph nodes in his armpits were so big. He was encased, front and back, by cancer. His doctors tried everything they could, but his outlook was considered hopeless.
With nowhere else to turn, J.D agreed to try the new experimental drug. At 10am on the 27th of August 1942 he was given the first injection of what they called "synthetic lymphocidal chemical". This was in fact nitrogen mustard, the compound used to make mustard gas. Because of the war, J.D.'s treatment was a secret and it was referred to in his records only as "substance X".
He received a number of treatments with substance X and with each one he became a little better. He could sleep, he could swallow and he could eat. He was much more comfortable and the pain faded away.
This was a monumental moment in the history of medicine. It was the beginning of what we now know as chemotherapy.