On this day in 1945, just before dawn, the world entered the atomic age. The Manhattan Project cost $2 billion ($20 billion today) and involved the largest group of brilliant minds ever assembled. Not too long after two bombs would be dropped on Japan, turning the largest science experiment in history into largest weapon of war ever used. It was estimated that in order to defeat the Japanese the largest invasion ever would have to be conducted, resulting in one million American casualties. Five million Japanese would have to be killed reaching Tokyo and forcing the government to surrender. The Russians would have invaded from the north, resulting in millions more dead and dividing the Japanese islands in two, one communist, one capitalist. The divided nation would eventually go to war to reunify the islands in a conflict that would make Korea look like a school yard squabble. For saving countless millions of lives and ending the war more than a year early, the overwhelming impetus toward world peace that was born on 16 July 1945 cannot be underestimated. There has not been another World War since. There has not been anything close to one, and we have the threat of nuclear annihilation to thank. It seems we humans are so primitive that we have to be scared straight, or at least less crooked.
Clip from "Trinity and Beyond"
Clip from The History Channel