On August 6 and 9, 1945, the US launched two nuclear bombs on the Japanese cities of Hiroshima and Nagasaki, the only attacks of this nature ever carried out against human targets to date.
The approximate number of deaths accounted for by the bombings is 140,000 in Hiroshima and 74,000 in Nagasaki.
the bombs little boy, launched in Hiroshima, and the Fat Man, in Nagasaki, led the Japanese to declare their surrender on August 14, 1945, with the officialization on September 2 of the same year.
The attacks destroyed both cities, in addition to sealing the end of World War II (1939-1945). With the bombings, the US sent a message to the world about the power of its war technology.
Other countries started nuclear projects in the following years, which led the world to experience the terror of a new and more powerful nuclear attack during the Cold War.
What prompted the United States to attack Japan?
The United States entered World War II only in 1941, after the Japanese attack on the American naval base in pearl harbor, which took place on December 7 of the same year.
Until then, the North Americans traded with the Allied countries (mainly France and England). This was one of the factors that led them to compose this group in the war.
Japan and the US had had diplomatic conflicts since the 1920s. During World War II, the Japanese invaded China and French Indochina, in 1941, in addition to the Philippines region, territory of North American domain.
The USA competed with the Japanese for hegemony in the Asian continent. Therefore, as a response during the war, the Americans imposed a trade embargo on the Japanese, prohibiting the sale of essential items with them.
Japanese retaliation took place on December 7, 1941, when the Japanese attacked the US naval base at Pearl Harbor, without there being a declaration of war between the nations. This factor was decisive for the Americans to enter the war.
From then on, armed conflicts between the countries began. After a victorious Japanese start, the Asians were weakening economically and militarily, with defeat being a practically certain end.
the nuclear bombs
Manhattan Project
The nuclear bombs of Hiroshima and Nagasaki were the result of the Manhattan Project. This ultra-secret US project brought together big names in science with aim of developing nuclear weapons.
The USA was afraid of Nazi Germany producing this war material before the Allies. This is what Einstein and Szilard wrote in the letter sent to US President Franklin Delano Roosevelt, claiming that German scientists were already developing studies on nuclear fission.
The Manhattan Project developed during Roosevelt's administration, but he died on April 12 of 1945, being his deputy, Harry Truman, the US president who authorized the launching of the bombs.
The first nuclear bomb developed from the Manhattan Project was the trinity, also the first to be detonated in the world. It was tested on July 16, 1945, a few months before the attacks on Japanese cities.
On July 26, 1945, Truman, in a statement, demanded the surrender of the Japanese, who had been weakened by the war. In an ultimatum, he said that if the Asians did not surrender, they would face "swift and absolute" destruction..
Weeks later, the meaning of that sentence would become clear to the world. Seeing that the Japanese did not comply with the ultimatum, the Americans decided to attack.
Characteristics of bombs dropped and chronology of bombings
A little boy, bomb used in Hiroshima, was three meters long by 70 centimeters in diameter and weighed four tons, with an explosive capacity of 15 tons of TNT.
A Fat Man, from Nagasaki, was 3.5 meters long and 1.5 meters in its maximum diameter, weighing 4.5 tons, composed of plutonium, with an explosive capacity of 20 tons of TNT.
The first city attacked was Hiroshima, on August 6, 1945. The B-29 bomber plane, called enola gay, piloted by Paul Tibbets, at 8:15 am, carried out the attack, launching the little boy, uranium 253 bomb. A strong flash formed with the explosion, creating a "small sun on Earth".
The heat wave created by the bomb reached 4000 °C, reaching a destruction radius of approximately 4.5 km. The force of the explosion could be felt 60 km away.
For 3 days there were fires in the city caused by the heat. Approximately 60% of the city was destroyed and 140,000 people died in that first attack.
Even with the material, human and psychological impacts caused by an attack that shocked the world, Japan decided not to surrender. However, three days after the first attack, on August 9, the US dropped a second bomb.
The initial target was the city of Kokura, with flat terrain, but the fog made it impossible for Charles to Sweeney, pilot of the B-29 bomber (the same model used in Hiroshima), managed to launch the bomb.
Like this, he headed towards the city of Nagasaki loading the Fat Man, bomb with an even greater destructive power than the previous one, made of plutonium 239. The bomb exploded 500 meters from the ground.
The force of the explosion Fat Man was larger, but the geographical characteristics of Nagasaki reduced the area of destruction, as there are two valleys between the city. Still, 40% of the city was destroyed.
Five days after the second attack, the Japanese declared their surrender on August 14, 1945. The agreement was signed on September 2, on the American ship USS Missouri, in Tokyo Bay.
You hibakushas, survivors of the nuclear attacks and the nuclear aftermath
Survivors of nuclear attacks are called hibakushas, Japanese word meaning “bomb exposed” or “bomb children”.
These individuals suffered from various health problems after the attack, with illnesses that manifested themselves only years later due to the radiation. In addition, cases of discrimination were commonplace.
Reports were common hibakushas with difficulties finding a job, marriage or even marrying their own children, due to people's fear of how radiation would manifest itself in their bodies or genes in the future.
In addition to the deaths and destruction, the survivors were left with consequences such as first-time burns. third-degree, retinal burns, cancerous tumors, genetic alterations, among other issues. In the long term, emotional problems, epidemic outbreaks of diseases such as tuberculosis, dysentery, hepatitis or other psychic and psychosomatic illnesses.
In the environment, it was possible to notice climate changes, increasing and lasting increase in the flow of solar ultraviolet radiation and changes in temperature in various regions of the planet.
Interpretations on the US attack and the end of World War II.
The attacks on Hiroshima and Nagasaki are a point of discussion among historians. The Americans argue that the bombings put an end to a conflict that would last longer and cost more lives later.
However, researchers say there was another goal: the US interest in demonstrating its technological power to the rest of the world, especially the USSR. This was evident with the Space Race of the Cold War.
About World War II
World War II was an armed conflict involving several countries that began in 1939 and ended in 1945. Two groups were formed: the Axis countries (Germany, Italy and Japan) and the Allies (England, France, USA and USSR). Brazil was part of the second group.
At the end of the conflict, the Allied countries were victorious, leaving the Axis forces with the loss of territories and the payment of indemnities.
Bibliographic references
RIBEIRO, Jayme. The "Children of the Bomb": memory and history between the reports of survivors of Hiroshima and Nagasaki and the "Campaign for the Prohibition of Atomic Bombs" in Brazil (1950). Other times, Maranhão, Volume 6, number 7, July 2009 - History and Memory Dossier. Available in: https://www.outrostempos.uema.br/index.php/outros_tempos_uema/article/download/192/132/615. Accessed on Sep 05, 2022.
SOUZA, Thiago. Atomic bombs on Hiroshima and Nagasaki: the history of nuclear attacks.All Matter, [n.d.]. Available in: https://www.todamateria.com.br/hiroshima-e-nagasaki/. Access at:
See too
- Hiroshima bomb
- Atomic Bomb: what it is and how it works
- Phases of the First World War
- Brazil in World War II
- Questions about World War II
- Manhattan Project
- Second World War
- pearl harbor
