"Stimson, what was gunpowder? Trivial. What was electricity? Meaningless. This atomic bomb is the second coming in wrath!" Those words were spoken by British Prime Minister Winston Churchill to U.S. Secretary of War Henry Stimson. The two men were gathered at the Potsdam Conference in July of 1945, and Churchill had just been informed that America had successfully exploded an atomic bomb.

In one sense, human history was transformed the moment that bomb exploded in the New Mexico desert. Nevertheless, it was the first use of an atomic bomb in warfare that is seared into the human memory. On August 6, 1945, Colonel Paul Tibbets and his crew flew the Enola Gay, their specially modified B-29 bomber, and dropped "Little Boy" over the city of Hiroshima, Japan.

The power and destructive force of the bomb defied the human imagination, and it continues to do so today. Within seconds of its detonation, the bomb had destroyed most of central Hiroshima. A giant fireball unleashed annihilation and a consuming inferno throughout the city. Buildings, bridges, and human bodies were evaporated by the force of the blast as successive shockwaves spread throughout the region and a now-familiar mushroom cloud reached heights of over 48,000 feet over the city. Just three days later, an even more destructive bomb would be dropped over the city of Nagasaki.

News of the bomb and its power soon spread around the world. Joseph Stalin had been informed of the American development of the bomb during the Potsdam Conference. According to historians, he then went into an entire day of mourning and seclusion. The actual use of the bomb could not be hidden from the human consciousness. Indeed, the American use of the bomb was intended to break the Japanese military's will to fight.

At first, the American people responded to news of the bomb with a sense of relief. This was especially true for millions of American soldiers, who knew that the alternative to a Japanese surrender was a ghastly invasion of the Japanese mainland. Just after dropping the bomb, navigator Theodore (Dutch) Van Kirk heard someone aboard the Enola Gay express, "This war is over." As Van Kirk later reflected, he silently agreed with the assessment. "You didn't see how anybody--even the most radical, militaristic, uncaring for their people--how anybody like that could stand up to something like this."

Writer Paul Fussell, a 21-year-old soldier serving in France and waiting for likely deployment for the Japanese invasion, expressed his thoughts with simple relief: "We were going to live. We were going to grow up to adulthood after all."

The actual destruction wrought by the bomb was classically described by novelist John Hersey in Hiroshima, first released as a book in 1946. Much of the book had already appeared in a series of articles Hersey wrote for The New Yorker. The human toll eventually numbered somewhere between 100,000 and 200,000 deaths. An estimated 120,000 were killed immediately in Hiroshima and Nagasaki but thousands of others died later from catastrophic injuries and the effects of radiation.