The Manhattan Project


The Manhattan Project was a secret military project created in 1942 to produce the first US nuclear weapon. Fears that Nazi Germany would build and use a nuclear weapon during World War II triggered the start of the Manhattan Project, which was initially based in Manhattan, New York. US physicist Robert Oppenheimer and General Leslie R. Groves served as directors of this project, which recruited some of the best US scientists, engineers, and mathematicians. European scientists, including Albert Einstein, Enrico Fermi, and Leo Szilard, also participated in the Manhattan Project.

Under the auspices of the Manhattan Project, three primary research and production facilities were established at Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico. The Oak Ridge Laboratories provided uranium-235, and Hanford produced weapons-grade plutonium. The Los Alamos Laboratory became the site for assembling nuclear weapons. Los Alamos had four weapons, two of which, Little Boy and Fat Man, were used against Japan in August 1945. The Manhattan Project officially ended in 1946 when it became part of the Atomic Energy Commission (AEC).

The Debate

The decision to drop the atomic bombs on the cities of Hiroshima and Nagasaki is one of the most controversial issues of the 20th century. Many modern historians have criticized the commonly held perceptions that the bomb shortened the war, saved American lives, and prevented the USSR’s sharing in Japan’s post-war administration (see, for example, Hiroshima’s Shadow, edited by Kai Bird & Lawrence Lifschultz ). In 1995, on the 50th anniversary of the bombing, an exhibit designed to commemorate the event resulted in unprecedented controversy for the Smithsonian Institution. The American Legion and other veteran organizations successfully lobbied against including quotes from several notables, including Dwight D. Eisenhower, that questioned the necessity of the bomb’s use.

The debate has not subsided. The decision to drop the first atomic bomb on Japan will remain relevant to our collective human experience forever. Important questions remain: Did it have to happen? Will it happen again in an even more catastrophic way? What do the first human experiences with nuclear power say about humanity’s ability to control its most dangerous creation?

The Atomic Bombs

Before any nuclear testing, the British government wrote about possibly incorporating atomic weapons in World War II. The MAUD report, as it is called, was a secret document produced by a British committee during World War II. It analyzed the feasibility of building an atomic bomb and recommended that Britain pursue its development. The report was named after the secretary of the committee, Maud Ray Kent.

President Truman authorized the use of atomic bombs against Japan in 1945, ending World War II. He made this decision based on the advice of his military and political advisers, who argued that it would save American lives and force Japan to surrender.

The first nuclear bomb testing was a historic event that marked the beginning of the atomic age. The test codenamed Trinity, took place on July 16, 1945, in the desert of New Mexico, USA. The bomb, nicknamed “the gadget,” was a plutonium implosion device with a yield of about 20 kilotons of TNT. The explosion created a fireball that rose to 12 kilometers and a mushroom cloud that reached 18 kilometers. The blast was felt hundreds of kilometers away, and the shockwave shattered windows in nearby towns, all witnessed by the following individuals:

Little Boy – Little Boy was one of the four nuclear weapons produced by the Manhattan Project at Los Alamos. It was the first atomic bomb ever used in combat. On August 6, 1945, the US plane Enola Gay dropped Little Boy approximately 1,800 feet over Hiroshima, Japan, with a force equal to 13,000 tons of TNT. Immediate deaths were between 70,000 to 130,000. Little Boy was a gun-type uranium-235 weapon, 10 feet long, 28 inches wide, and weighing 8,900 lb. It fired one subcritical piece of uranium-235 into another subcritical part of uranium-235, which caused a nuclear chain reaction.
Fat Man – The world’s third atomic bomb, a plutonium implosion device, explodes over Nagasaki, Japan. It has a yield of approximately 20 kilotons of TNT. Some 35,000 to 40,000 persons die immediately, and a total of 75,000 persons die from the bombing by the end of 1945.

Fat Man was approximately 60 inches wide, 128 inches long, weight 10,300 lbs, and had a yield of 21 kilotons TNT. The picture depicts a Fat Man bomb assembly being prepared for testing at the US Navy Saltwells ordinance facility near Inyokern, California (now China Lake Naval Weapons Center, near Ridgecrest, California).

Political Agreements

As a result of the United States’ decision to drop several atomic bombs, the government reached agreements with countries for assurance of their support of the US’s actions. Some of those agreement statements are outlined below: