| Term | Definition |
| Harry S. Truman | The 33rd U.S. president, who succeeded Franklin D. Roosevelt upon Roosevelt's death in April 1945. Truman, who led the country through the last few months of World War II, is best known for making the controversial decision to use two atomic bombs against Japan in August 1945. After the war, Truman was crucial in the implementation of the Marshall Plan, which greatly accelerated Western Europe's economic recovery. |
| August 6, 1945 | the Enola Gay dropped an atomic bomb on Hiroshima killing more than 75000 people |
| August 9, 1945 | Date of bombing on Nagasaki. |
| incendiary bomb | The incendiary bomb was a mixture of thermite and oxidizing agents employed by the Allies and Axis powers after 1943. Sometimes incorporating napalm, these bombs were responsible for burning over 41.5 square miles of Tokyo by the US in March 1945. |
| unconditional surrender | Unconditional surrender is a term used by victors in war to describe the type of settlement they wish to extoll from the vanquished. |
| providence | divine guidance or care. |
| ultimatum | the final propositions, conditions, or terms offered by either of the parties during a diplomatic negotiation. |
| radiation | energy that is radiated or transmitted in the form of rays or waves or particles |
| Enola Gay | the name of the American B-29 bomber, piloted by Col. Paul Tibbets, Jr., that dropped the atomic bomb on Hiroshima, Japan, on Aug. 6, 1945. |
| nuclear arms race | During the Cold War, Americans and Soviets would make large stockpiles of nuclear weapons. |