The United States dropped Little Boy, which is a uranium gun- category atomic bomb on the Japanese city Hiroshima on the 6th of August 1945. Soon this was followed by dropping of Fat Man, a plutonium implosion-category bomb on the other Japanese city, Nagasaki on the 9th of August 9 1945 by the United States. These two bombing incidents, killed a minimum of 129,000 citizens, remain the only application of nuclear weapons for fighting in human history.
As the World War II entered its 6th and final year, the Allies had started to get ready for, what was expected to be, an extremely expensive invasion of the mainland of Japan. This was preceded by a greatly destructive firebombing movement that destroyed many cities in Japan. The warfare in Europe had come to an end when Nazi Germany signed its implement of surrender on the 6th of May 1945, but with the refusal of Japan to agree to the demands of the Allies for unreserved surrender, made the Pacific War continued. Together with China and the United Kingdom, the United States demanded the unconditional give up of the armed forces of Japan during the Potsdam Declaration on the 26th of July 1945, was supported with the threat of "punctual and utter obliteration".
The Allied Manhattan Project had exploded an atomic device successfully in the New Mexico desert in August 1945 and subsequently manufactured atomic weapons derived from two alternating designs. The United States Army Air Forces 509th Composite Group was prepared with a 4-engine propeller-determined heavy bomber, the Superfortress Silverplate Boeing B-29, which could bring them from Tinian, an arc-shaped archipelago, the Mariana Islands. Within the initial two to four months of the Hiroshima and Nagasaki bombing incidents, the sensitive effects of the atomic bomb droppings killed citizens in Hiroshima, ranging from 90,000 to 166,000 and killed Nagasaki inhabitants between 39,000 and 80,000. It was approximately 50 % of the deaths in each Japanese city taken place on the first day. During the subsequent months, huge number of people died from the consequence of radiation sickness, burns, and other wounds, compounded by sickness and starvation. In both Hiroshima and Nagasaki cities, the majority of the dead were civilians, even though the Hiroshima City had a considerable military barracks.
Just days following the bombing of Nagasaki and the declaration of war by the Soviet Union, Japan declared its surrender to the Allies on the 15th of August 1945. On the 21st of September 1945, Japan signed the implement of surrender, successfully ending the Second World War. The role of the bombings in surrender of Japan and their moral justification are still under debate.
During the time of bombing, the Hiroshima city was an abode of both military and industrial significance. Many military units were situated nearby, the most important among them was the head office of the Second Army General, Shunroku Hata, the field marshal in the Imperial Army of Japan during the Second World War that controlled the defense of all of southern parts Japan, and was situated in Hiroshima Castle.
During the Second World War, the Nagasaki City had been one among the major seaports in the southern part of Japan, and was of huge wartime significance due to its extensive industrial activity, as well as the manufacture of weapons, military equipment, ships, and other battle materials.