Why did the US dropped the atomic bomb on japan?

Answer 1

Date of first bombing: August 6, 1945

In April and May 1945, Japan made three attempts through neutral Sweden and Portugal to bring the war to a peaceful end. On April 7, acting Foreign Minister Mamoru Shigemitsu met with Swedish ambassador Widon Bagge in Tokyo, asking him "to ascertain what peace terms the United States and Britain had in mind." But he emphasized that unconditional surrender was unacceptable, and that "the Emperor must not be touched." Bagge relayed the message to the United States, but Secretary of State Stettinius told the US Ambassador in Sweden to "show no interest or take any initiative in pursuit of the matter." Similar Japanese peace signals through Portugal, on May 7, and again through Sweden, on the 10th, proved similarly fruitless.
By mid-June, six members of Japan's Supreme War Council had secretly charged Foreign Minister Shigenori Togo with the task of approaching Soviet Russia's leaders "with a view to terminating the war if possible by September." On June 22 the Emperor called a meeting of the Supreme War Council, which included the Prime Minister, the Foreign Minister, and the leading military figures. "We have heard enough of this determination of yours to fight to the last soldiers," said Emperor Hirohito. "We wish that you, leaders of Japan, will strive now to study the ways and the means to conclude the war. In doing so, try not to be bound by the decisions you have made in the past."
By early July the US had intercepted messages from Togo to the Japanese ambassador in Moscow, Naotake Sato, showing that the Emperor himself was taking a personal hand in the peace effort, and had directed that the Soviet Union be asked to help end the war. US officials also knew that the key obstacle to ending the war was American insistence on "unconditional surrender," a demand that precluded any negotiations. The Japanese were willing to accept nearly everything, except turning over their semi-divine Emperor. Heir of a 2,600-year-old dynasty, Hirohito was regarded by his people as a "living god" who personified the nation. (Until the August 15 radio broadcast of his surrender announcement, the Japanese people had never heard his voice.) Japanese particularly feared that the Americans would humiliate the Emperor, and even execute him as a war criminal.
On July 12, Hirohito summoned Fumimaro Konoye, who had served as prime minister in 1940-41. Explaining that "it will be necessary to terminate the war without delay," the Emperor said that he wished Konoye to secure peace with the Americans and British through the Soviets. As Prince Konoye later recalled, the Emperor instructed him "to secure peace at any price, notwithstanding its severity."
The next day, July 13, Foreign Minister Shigenori Togo wired ambassador Naotake Sato in Moscow: "See [Soviet foreign minister] Molotov before his departure for Potsdam ... Convey His Majesty's strong desire to secure a termination of the war ... Unconditional surrender is the only obstacle to peace ..."
On July 17, another intercepted Japanese message revealed that although Japan's leaders felt that the unconditional surrender formula involved an unacceptable dishonor, they were convinced that "the demands of the times" made Soviet mediation to terminate the war absolutely essential. Further diplomatic messages indicated that the only condition asked by the Japanese was preservation of "our form of government." The only "difficult point," a July 25 message disclosed, "is the ... formality of unconditional surrender."
Summarizing the messages between Togo and Sato, US naval intelligence said that Japan's leaders, "though still balking at the term unconditional surrender," recognized that the war was lost, and had reached the point where they have "no objection to the restoration of peace on the basis of the [1941] Atlantic Charter." These messages, said Assistant Secretary of the Navy Lewis Strauss, "indeed stipulated only that the integrity of the Japanese Royal Family be preserved."
Navy Secretary James Forrestal termed the intercepted messages "real evidence of a Japanese desire to get out of the war." "With the interception of these messages," notes historian Alperovitz (p. 177), "there could no longer be any real doubt as to the Japanese intentions; the maneuvers were overt and explicit and, most of all, official acts. Koichi Kido, Japan's Lord Privy Seal and a close advisor to the Emperor, later affirmed: "Our decision to seek a way out of this war, was made in early June before any atomic bomb had been dropped and Russia had not entered the war. It was already our decision."
In spite of this, on July 26 the leaders of the United States and Britain issued the Potsdam declaration, which included this grim ultimatum: "We call upon the government of Japan to proclaim now the unconditional surrender of all Japanese armed forces and to provide proper and adequate assurance of good faith in such action. The alternative for Japan is prompt and utter destruction."
Commenting on this draconian either-or proclamation, British historian J.F.C. Fuller wrote: "Not a word was said about the Emperor, because it would be unacceptable to the Propaganda-fed American masses." (A Military History of the Western World [1987], p. 675.)
America's leaders understood Japan's desperate position: the Japanese were willing to end the war on any terms, as long as the Emperor was not molested. If the US leadership had not insisted on unconditional surrender -- that is, if they had made clear a willingness to permit the Emperor to remain in place -- the Japanese very likely would have surrendered immediately, thus saving many thousands of lives.
The sad irony is that, as it actually turned out, the American leaders decided anyway to retain the Emperor as a symbol of authority and continuity. They realized, correctly, that Hirohito was useful as a figurehead prop for their own occupation authority in postwar Japan.
On August 6, 1945, the world dramatically entered the atomic age: without either warning or precedent, an American plane dropped a single nuclear bomb on the Japanese city of Hiroshima. The explosion utterly destroyed more than four square miles of the city center. About 90,000 people were killed immediately; another 40,000 were injured, many of whom died in protracted agony from radiation sickness. Three days later, a second atomic strike on the city of Nagasaki killed some 37,000 people and injured another 43,000. Together the two bombs eventually killed an estimated 200,000 Japanese civilians.

Source: Weber, Mark "Was Hiroshima Necessary? Why the Atomic Bombings could have been avoided" The Journal of Historical Review, May-June 1997 (Vol. 16, No. 3), pages 4-11.