During the German air raid over the Italian port of Bari in 1943, an American ship carrying mustard gas was struck by one of the bombs. What was the US doing with the mustard gas at the time?

by Sonochu

Also do we know how much mustard gas (and other chemical weapons) were shipped over to Europe?

Georgy_K_Zhukov

More can be said, but this incident is touched on here.