On August 6, 1945, the United States became the first and only country to ever use the atomic bomb against another nation. The decision to bomb the Japanese cities of Hiroshima and Nagasaki is as controversial today as it was then. ABC's Peter Jennings goes behind the scenes of the Truman administration to uncover how the decision to drop the atomic bomb was reached. Did it shorten the war? Did it save lives? Was it necessary? While President Truman claimed he was in complete control of the situation, historians tell a different story. Also, see actual war footage and view the incredible destruction from the atomic bombs, including some of the human carnage that had been kept secret for decades. "I made the only decision I ever knew how to make. I did what I thought was right." - President Harry S. Truman.