Rife with "fateful risks" and swallowing over $2 billion, the fight was long and hard, but 63 years ago, the "battle of the laboratories" finally drew to a close.

On August 6, 1945, President Truman released a statement announcing the use of the atomic bomb at Hiroshima, declaring the U.S. "prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city."

For Americans who heard the announcement, the dropping of the A-bomb was a reflection of the "harnessing of the basic power of the universe," a celebration of one of the greatest scientific achievements of the era. For the Japanese, however, it meant over 70,000 citizens killed in a single day.

Naturally, the triumphant tone with which Truman affirmed the beginning of a "new era in man's understanding of nature's forces" was one that characterized the moment: proud, pleased, and satisfied to see the enemy "repaid many fold" at last. But if he thought the new era was to be a simpler one, he, and his presidential successors, were destined to be disappointed. For many, the time when "atomic power can become a powerful and forceful influence towards the maintenance of world peace" has yet to come.