Manhattan Project: The Making of the Atomic Bomb


By Patrick AllittEmory University

The length and the ferocity of the Second World War, and the anticipation of worse things to come in an invasion of Japan itself, was the context in which the American atomic bomb was perfected and then used. Read on to know more.

atom bomb explosion cloud
Enrico Fermi experimented with the atomic reaction to see if the same can be applied for military advances. (Image: Everett Collection/Shutterstock)

Japan’s Troublesome Tenacity

Once the war had been finished in Europe by May of 1945, it wasn’t at all clear to the American politicians or commanders that the war against Japan was also almost over. In fact, there were predictions that it might very easily take another five years, that for a long period into the future, the struggle against the Japanese was going to continue.

Estimates inside the army were that perhaps as many as a million American casualties might be suffered before Japan could finally be defeated.

The Conquering ‘Columbus’

Since before the Second World War had begun, nuclear physics had been rapidly developing as a realm of scientific endeavor. The possibility had already been raised that perhaps atomic fission, that is the breaking of atoms, could be exploited in the development of a weapon.

Enrico Fermi, an Italian scientist working in the United States at the University of Chicago, showed that a controlled nuclear reaction was possible. Fermi also recognized that there was potentially a military application.

The president was kept closely informed of this research, and had explained to Fermi that if—and when—the reaction succeeded, he, the president, should be notified with a coded message. The message was, “The Italian navigator has landed in the New World”, in other words, a reference back to Columbus. With Fermi himself being Italian, this was a way of notifying the president that it had worked.

This is a transcript from the video series A History of the United States, 2nd EditionWatch it now, on Wondrium.

The Manhattan Project

Congress approved the creation of the Manhattan Project, a secret program. Congress allocated money without being told what it was. They were just told to donate to it eventually about $2 billion per year, and its research would then go forward in secret.

The officer in charge of it was General Leslie Groves, and he organized three major sites where the research and development took place—Hanford, Washington; Oak Ridge, Tennessee, taking advantage of the electricity generated by the Tennessee Valley Authority; and Los Alamos, New Mexico.

A Pool of Knowledge and Resources

Groves had direct access to the United States Treasury if he needed more supplies or more equipment of any kind or more money, without any awkward questions being asked or publicity being given to the project.

On one occasion, General Groves requested 1,000 tons of silver, because he needed to use it for a special kind of wiring. Well, the Treasury gave him 1,000 tons of silver, but they included a memorandum that said: “In the Treasury, we do not speak of tons of silver. Our unit is the troy ounce.” One can imagine what an amazing request this must have been.

Several prominent German-Jewish scientists were also working on the Manhattan Project; people who would have stayed in Germany, had Hitler not persecuted the Jews, and certainly would have been able to give Germany an atomic bomb, had they stayed. British nuclear scientists had also gone to America to pool their knowledge and their resources with the Americans.

Who Did It First?

The Manhattan Project was, then, a very international business. Some of the best scientists from all over the world were collaborating to try to make this weapon. Of course, they were doing it in the knowledge that the enemy was trying to do it as well.

They felt themselves to be under intense pressure of a race, from fear that the Germans might perfect their atom bomb first and use it against the Allies. Hitler certainly hoped that would happen, and, of course, it was the kind of weapon that could have turned back the Allies improving fortunes in the war itself.

German scientists had split uranium atoms in Berlin back in 1939. Well, the first bomb was tested in the New Mexico desert on July 16, 1945, and it proved spectacularly successful. This was out at Alamogordo, one of the most low population density parts of the whole of America.

Harry Truman

Sculpture of Harry Truman
Truman faced a major dilemma after learning about the Manhattan Project. (Image: Vitaliy Berkovych/Shutterstock)

Meanwhile, in American politics, a dramatic changing of the guard had taken place. Just as President Roosevelt had run for a third term of office in 1940, so he’d also decided to run for a fourth term of office in 1944. Yet again, he’d won, because the Great War crisis enabled him to argue, quite plausibly, that his accumulated experience was important to keep at times of great national emergency.

Roosevelt had abandoned his old vice president, Henry Wallace, and introduced a new one, Harry Truman, though. However, shortly after Roosevelt’s re-inauguration in the spring of 1945, Roosevelt died, so Truman became president.

To Test or Not to Test?

Now, Roosevelt and Truman had not been close, and Roosevelt hadn’t told Truman about the development of the Manhattan Project. In fact, he hadn’t been privy to most foreign policy discussions at all.

Truman hadn’t known about research on the atom bomb. When he became president, one of the first things he was briefed on was the fact that this secret weapon project was going on, and that it was almost ready. He had to decide whether it should be used once the test had worked.

He shared his advisors’ belief that a conventional invasion of Japan would be very costly in lives and might take many years. Now, some of his advisors told him that America should make a demonstration. They should demonstrate this weapon to the Japanese in a neutral place as a way of saying to them, ‘If you don’t surrender now, then we’ll use it against Japanese cities’.

After a lot of speculation, Truman finally decided the weapon ought to be tested.

Common Questions about the Manhattan Project

Q: Who initiated the experiment on atomic bomb?

Enrico Fermi, an Italian scientist working in the United States at the University of Chicago, came up with the idea of using atomic explosion for military application.

Q: What was the site of research and development?

There were three major sites for the research and development—Hanford, Washington; Oak Ridge, Tennessee, taking advantage of the electricity generated by the Tennessee Valley Authority; and Los Alamos, New Mexico.

Q: Who was the president when the atomic bomb was to be tested?

Harry Truman was the president who had to decide on the testing of the bomb.

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