Yes, nuclear bombs have been used in warfare twice, both by the United States during World War II. On August 6, 1945, the United States dropped an atomic bomb named "Little Boy" on the Japanese city of Hiroshima. Three days later, on August 9, 1945, the United States dropped another atomic bomb named "Fat Man" on the Japanese city of Nagasaki. These bombings resulted in the deaths of hundreds of thousands of people and ultimately contributed to Japan's surrender and the end of World War II.