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Manhattan Project

The Secret U.S. Attempt to Create the First Atomic Bomb

By Shelly Schwartz, Contributing History Writer

Manhattan Project

Image labeled '0.053 Sec' of the first Nuclear Test, codenamed 'Trinity', conducted by Los Alamos National Laboratory at Alamogordo, New Mexico. (July 16, 1945)

(Photo by Fotosearch/Getty Images)
During World War II, American physicists and engineers began a race against Nazi Germany to create the first atomic bomb. This secret four-year endeavor (1942-1945) was code-named “the Manhattan Project,” named for one of the initial sites of research, Columbia University in Manhattan, New York. Headed by Brigadier General Leslie R. Groves (military head) and J. Robert Oppenheimer (scientific director), the Manhattan Project ultimately cost over two billion dollars. Research took place at secret sites across the U.S., but much of it took place near Los Alamos, New Mexico.

A Race Against the Germans

In 1938, German scientists discovered fission, which occurs when the nucleus of an atom breaks into two equal fragments that release neutrons that break up more atoms, causing a chain reaction. Since significant energy is released in only millionths of a second, it was thought that this could cause an explosive chain reaction of considerable force inside a uranium bomb.

In 1939, Leo Szilard and other American scientists, many of whom had recently emigrated from Europe, wanted to warn the U.S. government about the dangers of this new discovery. Not able to get a response from the government on their own, Szilard contacted and met with Albert Einstein, one of the most famous scientists of his day.

Albert Einstein, a devoted pacifist, was at first reluctant to contact the government to ask them to work toward creating a weapon that could potentially kill millions of people. However, Einstein was eventually won over by the threat of Nazi Germany having this weapon first.

On August 2, 1939, Einstein wrote a now famous letter to President Franklin D. Roosevelt outlining both the potential uses of an atomic bomb and ways to help support American scientists in their research. In response, President Roosevelt created the Advisory Committee on Uranium in October 1939.

Based on the recommendations of the committee, the U.S. government outlaid $6,000 to buy graphite and uranium oxide for research (scientists wanted the graphite to see if it could slow down a chain reaction).

Despite immediate action being taken, progress was slow until the U.S. officially entered World War II.

Development of the Bomb

On December 7, 1941, the Japanese military bombed Pearl Harbor, Hawaii, the headquarters of the United States Pacific Fleet. In response, the U.S. declared war on Japan the next day, thus entering WWII.

With the country at war and the realization that the United States was now three years behind Nazi Germany, President Roosevelt was ready to seriously support U.S. efforts to create an atomic bomb.

Costly experiments began at the University of Chicago; U.C. Berkeley; Columbia University in New York; Hanford, Washington; and Oak Bend, Tennessee (the site for uranium production). Reactors were built at Hanford and Oak Bend. Plutonium was chemically separated from the uranium.

With danger and difficulties encountered in developing nuclear weapons at scattered universities and towns, the need for an isolated laboratory away from the populace became a priority.

In 1942, Manhattan Project scientific director J. Robert Oppenheimer suggested the remote area of Los Alamos in New Mexico. General Groves approved the site and construction began at the end of 1942. Oppenheimer became the director of the Los Alamos Laboratory (known as “Project Y”).

Throughout 1942, research had been kicked into high gear. Then, on December 2, 1942 at the University of Chicago, Enrico Fermi created the very first successful chain reaction, in which atoms were split in a controlled environment. This accomplishment gave renewed vigor to the hopes that an atomic bomb was possible.

Scientists continued to work diligently but it took until 1945 to produce the first nuclear bomb.

The Trinity Test

When President Franklin Roosevelt died on April 12, 1945, Vice President Harry S. Truman became the 33rd president of the United States. Until then, Truman had not been told of the Manhattan Project and so he had to be briefed on the secrets of the atomic bomb development.

That summer, a test bomb was taken to the New Mexico desert. The code name “Trinity” (a name chosen by Oppenheimer in reference to a poem by John Donne) was given to the testing of the first bomb as it ascended to the top of a 100-foot tower. Having never tested anything of this magnitude before, everyone was anxious; while some scientists feared a dud, others feared the end of the world. No one knew what to expect.

At 5:30 a.m. on July 16, 1945, scientists, army personnel, and technicians donned special goggles to watch the beginning of the atomic age. The bomb was dropped, which was followed by a forceful flash, a wave of heat, a stupendous shock wave, and a mushroom cloud that extended 40,000 feet into the atmosphere. The tower was completely disintegrated and thousands of yards of surrounding desert sand had turned into glass.

The bomb had worked.

Using the Bomb to End WWII

Germany surrendered on May 8, 1945, two months before the successfully Trinity test; however, Japan refused to surrender despite threats from President Truman that terror would fall from the sky. After six years of war involving most of the globe, 61 million people killed, hundreds of thousands of displaced, homeless Jews, the last thing the U.S. wanted was a ground war with Japan.

On August 6, 1945, an atomic bomb named “Little Boy” (named for its relatively small size of ten feet in length and less than 10,000 pounds) was dropped on Hiroshima, Japan. Thousands of Japanese were killed, burned, and/or suffered radiation sickness. On August 9, 1945, when Japan still refused to surrender, a second bomb, named “Fat Man” (due to its rotund shape), was dropped on Nagasaki, Japan. Japan surrendered on August 14, 1945, thus ending WWII.

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