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Atomic Bomb
The atomic bomb, and nuclear bombs, are powerful weapons that use nuclear reactions as their source of explosive energy. Scientists first developed nuclear weapons technology during World War II. Atomic bombs have been used only twice in war—both times by the United States against Japan at the end of World War II, in Hiroshima and Nagasaki. -
Penicillin
During World War II, penicillin was mass-produced and used to fight infections among soldiers. Throughout history, infections had killed more soldiers than battle injuries, Markel wrote. "In World War I, the death rate from bacterial pneumonia was 18 percent; in WWII, it fell to less than 1 percent.".