The process of building the two atomic bombs was long and difficult. The Manhattan Project employed 120,000 people and cost nearly $2 billion. Although 120,000 Americans worked on the project, only a select group of scientists knew about the development of the atomic bomb. Vice President Truman never knew of the development of these bombs until he became president. The Axis powers did not know what was happening with the development of the atomic bomb; there was a Soviet spy in the project. The Soviet spy was named Klaus Fuchs, and he became one of the few people to know about the bombs. In the summer of 1945, Robert Oppenheimer was ready to test the first atomic bomb. On July 16, 1945, the bomb was tested. The bomb was tested at the Trinity site and was attached to a 100 foot high tower. Scientists were not fully prepared for the power of the atomic bomb. The flash of the explosion could be seen 200 miles away and the mushroom cloud reached nearly 40,000 feet high. The force of the explosion shattered windows of surrounding homes within a 100-mile radius of the test site. The powerful explosion had created a crater half a mile wide; the heat from the bomb transformed the sand into glass. The atomic bombs were unlike any bomb ever seen before. The test bomb explosion was 100 times more powerful than the most powerful bomb ever created before. When the bombs were being developed, no scientist knew if they would actually work. Even until the day of the bombings, scientists did not know whether the bombs would explode or simply fall to the ground. Although there were test bombs, each bomb was different, making the scientist unsure of explosions at any time. In the United States, a dud...... middle of paper ......e End of World War II: A Collection of Primary Sources. http://www2.gwu.edu/~nsarchiv/NSAEBB/NSAEBB162/ (accessed April 7, 2014). A&E Television Networks. "Yalta Conference". History.com. http://www.history.com/topics/world-war-ii/yalta-conference (accessed May 10, 2014). Independence Hall Association. “The Manhattan Project.” ushistory.org. http://www.ushistory.org/us/51f.asp (accessed May 3, 2014). "Atomic Bomb-Truman Press Release-August 6, 1945." Atomic Bomb-Truman Press Release-August 6, 1945. http://www.trumanlibrary.org/teacher/abomb.htm (accessed April 19, 2014). Independence Hall Association. “The decision to drop the bomb.” ushistory.org. http://www.ushistory.org/us/51g.asp (accessed April 11, 2014). Hall, Michelle. “By the numbers: the atomic bombs of World War II.” CNN. http://www.cnn.com/2013/08/06/world/asia/btn-atomic-bombs/ (accessed March 30, 2014).