The nuclear destruction of Japan – the history of the construction of the first atomic bombs

When a heavy bomber B-29 was distancing itself from the Japanese city of Hiroshima, on which the crew just dropped the first atomic bomb in history, the second pilot of the “flying fortress” – Robert A. Lewis, seeing the exodus of almost 80,000 people underneath them, screamed: “My God, what have we done?”
The American did not know that in addition to the complete destruction of a large city, his crew had contributed to the end of World War II in the Pacific and the start of the nuclear arms race between the world’s superpowers.

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On August 10, 1945, at 2:30 a.m., the Japanese Supreme War Council listened with attention to the words of its Emperor. Hirohito, the Son of the Sun, addressed his countrymen in this way:

“We have resolved to endure the unendurable and suffer what is insufferable.”

This, of course, meant the unconditional surrender of Japan as a direct consequence of more than three years of fighting, which ended in the American Boeing B-29 Superfortress dropping the first nuclear bombs in the history. The targets were the Japanese cities of Hiroshima and Nagasaki.

On August 6, a group of four B-29 bombers appeared in the sky above Hiroshima. One of them, called “Enola Gay” by its commander, dropped a 4-ton bomb with the code name “Little Boy” on the Japanese city. The explosion occurred 43 seconds after being dropped, 500 meters above the ground, and the nuclear mushroom, which quickly formed over the city, was several kilometers high. “Little Boy” literally razed the Japanese metropolis to the ground, destroying or severely damaging 70 thousand of the 76 thousand buildings standing there. 30% of the population of Hiroshima, i.e. at least 78,000 people, died. Those residents who were within 400 metres from the epicentre of the explosion simply evaporated, and in some cases there was only a trace left on the concrete. Severe burns were received by people staying even 3.5 km from the place of detonation of “Little Boy”.

Destroyed Hiroshima after August 6, 1945
Source: U.S. Navy via Wikimedia Commons

Despite the enormity of the tragedy, the incredible destruction and the mere fear of “terrible American weapons”, Japan did not surrender on August 6 or the day after. The emperor was convinced that the Americans certainly had only one bomb and that the danger had passed. Japan intended to defend itself to the very end – to the last soldier, to the last bullet, to the last ship. The steadfastness of the imperial defense was demonstrated, among others, by the defense of Iwo Jima and suicide attacks of the “divine wind”, which, shouting the name of the emperor, drove into the ships of the US Navy. The victory of Iwo Jima is one of the most bloody pages in the history of American Marines and the only battle in the Pacific war, where the losses of the attacking Americans (killed and wounded) were higher than those of the defending Japanese.

There were terrible carpet bombing raids on Tokyo, including that of March 9/10, 1945, during which 334 B-29 bombers dropped 1667 tons of incendiary bombs on the Japanese capital, burning 277,000 buildings and killing about 80,000 people – more than during the extermination of Hiroshima.

It was only the second nuclear attack on another Japanese city, Nagasaki, that forced Emperor Hirohito to accept the fact that he had lost the war and to put the country into the hands of the Americans. The Second World War in the Pacific ended with the signing of the unconditional surrender of Japan on September 2, 1945 on the Missouri battleship.

The construction and use of the atomic bomb changed the world – it ended one global conflict, started a massive arms race, changed the distribution of power on the planet and forced the development of new war strategies. How did the design of the first atomic bomb come about and why did the Americans care so much about the time of its construction?

Robert Oppenheimer  & general Leslie Groves at the Trinity Test site
Source: U.S. Army Corps of Engineers via Wikimedia Commons

The United States had been conducting research into the uranium element since 1939, but this work was initially of little priority. In February 1941, only $6,000 was allocated for the study of the atomic bomb, compared to 1945 when it was already in use… 2 billion dollars. Since 1942, the work to build the American nuclear explosive was called the “Manhattan Project”. In the city of Los Alamos, located in the state of New Mexico, more than 60 km from the nearest city, a secret center was established where the most prominent atomists of that time were gathered. As Sławomir Gowin wrote in his book “Hiroshima and Nagasaki”: “it’s no exaggeration to say that if one of the brilliant physicists wasn’t there, it meant he was working in Germany or the Soviet Union”. The American team was led by Robert Oppenheimer, a university professor from Berkeley.

After more than three years of work and effort by many people not only in Los Alamos, but also in other laboratories, the Manhattan Project was coming to an end. The first ever test of nuclear weapons, called by Oppenheimer “Trinity”, was to take place on July 16, 1945 in a desert near the city of Alamogordo, New Mexico.

The bomb was placed on a 30-metre high tower in order to simulate the explosion that was to take place after the bomb was dropped from an aeroplane. The training ground watched, hidden in the bunkers, the majority of the crew from Los Alamos. Interestingly, the scientists were not entirely sure about the exact force of the explosion, because they predicted an explosion that would have a force equal to the detonation of one hundred to several thousand tons of TNT. After the test was finished, it was calculated that it was as much as 20 thousand tons.

When the bomb went off, every life was annihilated up to 1600 meters from the epicentre of the blast, the temperature was three times the surface of the Sun, and the trembling of the windows in the buildings was felt up to 320 km from Alamogordo!

Nuclear explosive during the Trinity test.
Source: Jack W. Aeby via Wikimedia Commons

The effect of the detonation of the charge was terrible. Robert Oppenheimer, head of the scientists working on the Manhattan Project, said so a few hours after the explosion:

“Now, I am become Death, the destroyer of worlds.”

The reactions of the other scientists were similar. Terror prevailed, and there was a feeling of creating a weapon that would become a turning point in history and change the rules of war forever.

On the same day, the President of the United States, Harry Truman, received a telegram of the following content: “Operated on this morning. Diagnosis not yet complete but results seem satisfactory and already exceed expectations. Local press release necessary as interest extends great distance. Dr. Groves pleased. He returns tomorrow. I will keep you posted.” that coded message meant the success of the test of the first nuclear bomb in history. Truman already knew that he was the winner of the atomic race: Soviet scientists were far behind the Americans, and the German laboratory in Haigerloch (where the German bomb was being built) was taken over by the Allies. The success of the Manhattan Project was beneficial to the president for two reasons:

Firstly, the drop of the atomic bomb on Japan was intended to help Americans avoid massive loss of life during a further land offensive in the Far East. The closer American ships were to Tokyo, the greater the resistance of Japanese defenders. General Douglas MacArthur counted that defeating Japan will cost the United States even half a million more lost soldiers! Even though they were certain of their ultimate victory, the Americans preferred to use a new bomb against the Emperor rather than face the Japanese infantry, the rest of the fleet and the kamikaze pilots for months to come.

Photograph taken during the Potsdam Conference. In the bottom row in the middle, proud of his scientists president Harry S. Truman.
Source: Presidential Collection of Harry S. Truman, via Wikimedia Commons

Secondly, Truman was able to satisfy his vanity and a day later, on the first day of the Potsdam Conference, he did not fail to show off his success to Joseph Stalin. The American President was happy to have such a strong bargaining position at the very beginning of the conference. The atomic bomb was supposed to bring him political capital – although the USSR’s accession to the war against Japan was supposed to help defeat the common enemy faster, Truman did not want to share his later influence with Stalin in the occupied country. The goal was clear: it would be the United States which would bring Emperor Hirohito and his troops to their knees.

Stalin’s reaction to this shocking news was very calm, which surprised Truman. As it turned out later, the Soviet dictator knew perfectly well about the work on the American atomic bomb and the Trinity test itself, thanks to his numerous spies operating in the USA, including Klaus Fuchs, a scientist from Los Alamos. The activity of Soviet intelligence during the Manhattan Project and their subsequent acquisition of complete bomb construction plans is a topic for a separate extensive and interesting article.

After both bombs were dropped on Japan, Clark Clifford, the President’s advisor, asked President Harry Truman how he slept at the time. The President replied briefly: “Normally, just like every night”. On that day, Truman did not yet know that the nuclear annihilation of two Japanese cities ended World War II, but was starting a second conflict – the Cold War, an arms race that took place not on the battlefields, but in the offices of politicians and intelligence agencies.

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