On August 6, 1945, the United States dropped the first of two atomic bombs on the Japanese city of Hiroshima, killing more than 70,000 people instantly.
A second bomb followed three days later over Nagasaki, killing 40,000 more.
The United States remains the only country to have used an atomic bomb in a war.
The nuclear war marked the end of World War II and a devastating chapter in world history. Here’s what you need to know about attacks.
The bombing
In 1945, Hiroshima had between 300,000 and 420,000 people, according to the Department of Energy and the Hiroshima City website.
Then-President Harry S. Truman authorized the attack on Hiroshima. The US B-29 bomber, the Enola Gay, dropped the nuclear bomb, codenamed “Little Boy,” on August 6, 1945.
Why did it do it?
American scientists working on the Manhattan Project had successfully tested an atomic bomb in July 1945, after Nazi Germany surrendered in May.
Truman had commissioned an advisory committee, chaired by Secretary of War Henry Stimson, to deliberate whether the atomic bomb should be used against Japan.
Sam Rushay, the supervising archivist at the Harry S. Truman Presidential Library in Independence, Missouri, told Citizen Free Press: “At that time there was broad consensus among committee members in support of the decision to attack. Stimson was very firm on the what the pump should be used for.”
Charles Maier, a professor of history at Harvard University, said that while Truman might make another decision, he said: “It would have been difficult to justify to the American public why the war dragged on, when this weapon was available.”
“It seemed to offer a magic solution that could potentially save a lot of pain,” he told Citizen Free Press.
Maier, who teaches a course on World War II, said Japan was unwilling to surrender unconditionally and there were concerns that a weapons demonstration would not have been enough.
Such a demonstration would have been to detonate a nuclear weapon in an uninhabited but observable area to force Japan to surrender, an approach favored by a group of scientists and Assistant Secretary of War John McCloy, according to Rushay.
He added that Truman and his military advisers feared a “very costly invasion” in Japan.
“The recent experience in the battles of Iwo Jima and Okinawa was very costly in terms of American and Japanese casualties, despite the destruction of the Japanese air force and navy,” Rushay said. “There was a widespread belief among American military planners that the Japanese would fight to the last man.”
Maier said: “Suicide attacks are quite common today, at the time, Japan’s use of suicide kamikaze attacks had had a strong psychological impact on the high-ranking US military who believed that the entire country would mobilize to defend the islands.”
“The US military was not prepared to say that it could win the war without the bomb,” he added.
Maier said that some historians have speculated that the possibility of the Soviet Union’s entry into the war helped spur a decision to bring the war to a quick end through the use of the atomic bomb.
Rushay said that Hiroshima was one of four potential targets and that Truman left it up to the military to decide which city to attack. Hiroshima was targeted because of its military importance. Nagasaki was bombed a few days later.
The US remains the only country that has used nuclear weapons.
Which it was the result?
At least 70,000 people died in the initial blast, while approximately 70,000 more died from radiation exposure. “The five-year death toll may have reached or even exceeded 200,000, due to cancer and other long-term effects,” according to the Department of Energy’s story on the Manhattan Project.
The US dropped another bomb on Nagasaki, Japan, on August 9, 1945, killing 80,000 people. Japan unconditionally agreed to accept the surrender terms on August 14.
What do the critics say?
The devastation caused by the bombing led many to criticize the decision.
In his 1963 memoir, “Mandate for Change,” former President Dwight D. Eisenhower criticized the use of atomic bombs, saying they were not necessary to force Japan to surrender.
Maier said the Hiroshima and Nagasaki bombings “succeeded in prompting the Japanese emperor to intervene with a divided army and advocate surrender.” However, he added that Japan may have been willing to end the war on conditions such as keeping the emperor.
In 1958, the Hiroshima City Council passed a resolution condemning Truman for refusing to express remorse for using atomic bombs and for continuing to promote their use in an emergency situation.
The resolution said that city residents “consider it their sublime duty to be the cornerstone of world peace and no nation in the world should ever allow itself to repeat the mistake of using nuclear weapons.”
The resolution calls the former president’s stance a “grave disgrace committed against the people of Hiroshima and its fallen victims.”
The defense
Truman responded to the Hiroshima resolution by writing a letter to the president of the Council, saying that “the sentiment of the people of his city is easy to understand, and I am not in any way offended by the resolution.”
However, Truman stressed the need for the decision by referring to how the US had been “stabbed in the back” in Japan’s attack on Pearl Harbor and said the decision to use the two nuclear bombs He saved the lives of 250,000 Allied soldiers and 250,000 Japanese by helping to prevent an invasion.
“As the executive personnel who ordered the dropping of the bomb, I believe that the sacrifice of Hiroshima and Nagasaki was urgent and necessary for the prospective well-being of Japan and the allies,” Truman concluded.
How do Americans and Japanese feel about it?
A 2015 Pew Research Center survey found that only 14% of Japanese thought the bombing was justified, while 79% said it was not.
A Gallup poll conducted immediately after the bombing in 1945 found that 85% of Americans approved of Truman’s decision. However, the Pew poll last year found that the proportion of Americans who believe the use of nuclear weapons against Japan was justified had fallen to 56%.