This ship is best known for carrying a secret cargo of mustard gas and whose sinking by German aircraft in December 1943 at the port of Bari in south Italy caused an unintentional release of chemical weapons.

After stopping for an inspection by an officer of the 7th Chemical Ordnance Company at Augusta, Sicily on 26 November, the John Harvey sailed through the Strait of Otranto to arrive at Bari.

[4] Nearly all crewmen of John Harvey perished in the sinking; this prevented the rescuers from knowing the real nature of the danger until an M47A1 bomb fragment was retrieved from the wreckage.

This discovery was further investigated by pharmacologists, Louis S. Goodman and Alfred Gilman who had started in August 1942 a research on a mustard gas related agent, mustine, as the first chemotherapy treatment.

[5] Reports were purged or classified but, since there were too many witnesses to keep the secret, in February 1944, the U.S. Chiefs of Staff issued a statement admitting to the accident and emphasizing that the U.S. had no intention of using chemical weapons except in the case of retaliation.