The creation of the atomic bomb changed world history and the way we view war and national security.
Here's the publisher's description of the book:
In a national survey at the turn of the millennium, journalists and historians ranked the dropping of the atomic bomb and the surrender of Japan to end the Second World War as the top story of the twentieth century. The advent of nuclear weapons, brought about by the Manhattan Project, not only helped bring an end to World War II but ushered in the atomic age and determined how the next war—the Cold War—would be fought. The Manhattan Project also became the organizational model behind the impressive achievements of American “big science” during the second half of the twentieth century, which demonstrated the relationship between basic scientific research and national security.