The insecticidal properties of DDT were discovered in 1939 by Swiss chemist Paul Hermann Müller (who won the Nobel Prize for it in 1948). The Allied military quickly recognized its potential: in wartime conditions, insect-borne diseases like typhus, malaria, and dengue fever killed and disabled more soldiers than enemy action.
DDT's first dramatic deployment came in Naples in 1943-44 during a typhus outbreak. Health workers dusted over a million civilians with DDT powder, stopping the epidemic cold—the first time in history that a winter typhus outbreak had been halted. In the Pacific, DDT spraying of barracks, camps, and surrounding areas dramatically reduced malaria rates.
During the war, approximately 3 million military and civilian personnel were dusted or sprayed directly with DDT. Troops carried DDT powder in their equipment. The chemical was considered so safe that soldiers applied it liberally to their bodies, clothing, and bedding. It wasn't until Rachel Carson's "Silent Spring" in 1962 that DDT's devastating environmental effects—particularly on bird populations—became widely understood.