he decision to drop the atomic bomb was not a group decision, in the end president Harry S. Truman made it. Among the president's senior military commanders most felt that a massive invasion of Japan would probably be needed to end the war, although each service still wanted to claim ultimate victory for itself. The Navy said that its ongoing blockade of Japan would eventually force surrender. Likewise, the Army Air Force saw victory in continuing the fire bombing raids by B-29 bombers now close to a 1,000 that were eventually laying waste to huge areas of Japanese cities. Of course the Army felt strongly that only an invasion and occupation by troops would take care of complete victory. The atomic bomb dropped on the city of Hiroshima . The design is using a gun type arrangement to force a sub-critical mass of uranium-235 and three U235 target rings together at high velocity causing a chain reaction. It was explode able. The atomic bomb also dropped on Nagasaki. The Atomic bombs killed a lot of people. People had to suffer while burning down to death. In the picture below you can see that a lot of people got burned and had rashes all over their body.