Nitrogen mustards were developed in the 1920s and ’30s as agents of chemical warfare. By the 1940s, however, it had become clear that at least one of these compounds, HN-2, also known as mechlorethamine, was better suited for use in the fight against cancer, specifically against human lymphomas, than it was in the fight between Axis and Allied powers. In 1949 mechlorethamine became the first drug approved by the U.S. Food and Drug Administration for the treatment of cancer.