During World War II nitrogen mustards were studied at the Yale School of Medicine by Alfred Gilman and Louis Goodman, and classified human clinical trials of nitrogen mustards for the treatment of lymphoma started in December 1942. Also during World War II, an incident during the air raid on Bari, Italy, led to the release of mustard gas that affected several hundred soldiers and civilians. Medical examination of the survivors showed a decreased number of lymphocytes. After World War II was over, the Bari incident and the Yale group's studies eventually converged prompting a search for other similar compounds. Due to its use in previous studies, the nitrogen mustard known as "HN2" became the first chemotherapy drug mustine.