On Aug. 6, 1945, the United States dropped an atomic bomb (code-named “Little Boy”) on Hiroshima, Japan, that instantly killed an estimated 66,000 people in the first use of a nuclear weapon in warfare.

President Truman issued the following statement:
“It was to spare the Japanese people from utter destruction that the ultimatum of July 26 was issued at Potsdam. Their leaders promptly rejected that ultimatum. If they do not now accept our terms they may expect a rain of ruin from the air, the like of which has never been seen on this earth. Behind this air attack will follow sea and land forces in such number that and power as they have not yet seen and with the fighting skill of which they are already well aware.”

The second atomic bomb detonated over Nagasaki on August 9.