secondary source
"On August 6, 1945, during World War II (1939-45), an American B-29 bomber dropped the world’s first deployed atomic bomb over the Japanese city of Hiroshima. The explosion wiped out 90 percent of the city and immediately killed 80,000 people; tens of thousands more would later die of radiation exposure. Three days later, a second B-29 dropped another A-bomb on Nagasaki, killing an estimated 40,000 people. Japan’s Emperor Hirohito announced his country’s unconditional surrender in World War II in a radio address on August 15, citing the devastating power of “a new and most cruel bomb.” By the time of the Trinity test, the Allied powers had already defeated Germany in Europe. Japan, however, vowed to fight to the bitter end in the Pacific, despite clear indications (as early as 1944) that they had little chance of winning. In fact, between mid-April 1945 (when President Harry Truman took office) and mid-July, Japanese forces inflicted Allied casualties totaling nearly half those suffered in three full years of war in the Pacific, proving that Japan had become even more deadly when faced with defeat. In late July, Japan’s militarist government rejected the Allied demand for surrender put forth in the Potsdam Declaration, which threatened the Japanese with “prompt and utter destruction” if they refused.
General Douglas MacArthur and other top military commanders favored continuing the conventional bombing of Japan already in effect and following up with a massive invasion, codenamed “Operation Downfall.” They advised Truman that such an invasion would result in U.S. casualties of up to 1 million. In order to avoid such a high casualty rate, Truman decided–over the moral reservations of Secretary of War Henry Stimson, General Dwight Eisenhower and a number of the Manhattan Project scientists–to use the atomic bomb in the hopes of bringing the war to a quick end. Proponents of the A-bomb–such as James Byrnes, Truman’s secretary of state–believed that its devastating power would not only end the war, but also put the U.S. in a dominant position to determine the course of the postwar world."
Citation:
History.com Staff. "Bombing of Hiroshima and Nagasaki." History.com. A&E Television Networks, 2009. Web. 9 June 2016.
Explanation and significance:
The bombing of Hiroshima and Nagasaki devastated Japan, as hundreds of thousand of people died from the atomic bomb that the U.S. dropped, and later from radiation poisoning. The two bombs dropped, “The Little Boy” (dropped on Hiroshima) and “Fat Man” (dropped on Nagasaki), were the only two atomic bombs ever dropped during war, other countries were deterred to use them, as the effects of the bomb are brutal and the bomb is capable of wiping out entire cities. After World War II, the United States and the Soviet Union engaged in an arms race, as each country built more and more nuclear warheads. This became known as the Cold War. The Soviet Union and the United States had starkly contrasting economic ideologies; the USSR was a communist dictatorship and the USA was a democracy with a communist economy. This clash of cultures led to a feeling of distrust starting in the late 1940s.