The Manhattan Project was chiefly carried out in three secret locations at Hanford, Washington, Oak Ridge, Tennessee and Los Alamos, New Mexico. The Manhattan Project produced the atomic bombs, "Fat Man" and "Little Boy" that were dropped on Hiroshima and Nagasaki and ended WW2.

What was the Purpose of the Manhattan Project? The purpose of the Manhattan Project was to develop an Atomic Bomb. The Little Boy atomic bomb dropped on Hiroshima and the "Fat Man" atomic bomb was dropped on Nagasaki

Why was it called the Manhattan Project? It was called the Manhattan Project because the program began under the Manhattan Engineering District of the War Department and its scientists worked in Columbia University in Manhattan, NY

When did the Manhattan Project start? The Manhattan Project started on May 12, 1942 when President Roosevelt signed an order creating a top secret project to develop the nuclear weapon. 

Why was the Manhattan Project kept top secret? The Manhattan Project was kept top secret for fear that the nuclear technology would be stolen by enemy spies belonging to Germany or Japan or fall into the hands of the Russians. Info about the Manhattan Project could be used to accelerate their own nuclear projects or to mount covert operations against the project.

Who were the Manhattan Project scientists?
The famous scientists who worked on the Manhattan Project included Robert Oppenheimer, Enrico Fermi, David Bohm, Leo Szilard, Vannevar Bush, Walter Zinn , David Bohm, Herbert L. Anderson, Eugene Wigner, Otto Frisch, Rudolf Peierls, Felix Bloch, John R. Dunning, Niels Bohr, Emilio Segre, James Franck, Ernest O. Lawrence, Klaus Fuchs, Arthur Wahl and Edward Teller.

Was Albert Einstein involved in the Manhattan Project?
Hungarian physicist Leo Szilard was a friend and colleague of Albert Einstein and well known for his pioneering work in nuclear physics. Leo Szilard was the first to realize that nuclear power could be used to build a bomb of terrifying proportions. The only involvement Albert Einstein had in the Manhattan project were letters sent to President Roosevelt. Albert Einstein first put his name to a letter, dated August 2, 1939, written by Leo Szilard that was sent via Alexander Sachs to FDR.  Alexander Sachs, a trusted advisor, had access to President Franklin D. Roosevelt. The letter informed the President  that "a nuclear chain reaction in a large mass of uranium" was undoubtedly possible, and could lead to the construction of "extremely powerful bombs of a new type".

The letter,  signed by Einstein, also warned that Germany might  be developing a nuclear weapon. In response to the letter FDR set up the Advisory Committee on Uranium to investigate the issue. The committee were not convinced by the scientists and remained skeptical about the warning. Einstein sent two more letters to President Roosevelt, on March 7, 1940, and April 25, 1940, calling for action on nuclear research. In 1941 the committee were finally convinced when they met with British scientists, who were already working on an atomic bomb, and read the MAUD (Military Application of Uranium Detonation) report on the British atomic bomb project. President Roosevelt signed an order creating a secret project, called the Manhattan Project, to develop the nuclear weapon. The reason Albert Einstein was not included in the Manhattan Project was because in July 1940 the U.S. Army Intelligence office had denied Albert Einstein the security clearance required to work on the top secret Manhattan Project.

Facts about Manhattan Project Facts
The following fact sheet contains interesting facts and information on Manhattan Project Facts.

Science fiction writer H. G. Wells wrote about the idea of using "Atomic Bombs" in his 1914 novel 'The World Set Free' and predicted aerial bombardment and an imminent devastating world war.

US physicist Robert Oppenheimer and General Leslie R. Groves served as directors of the Manhattan Project

The Manhattan Project employed 130,000 workers and, by the end of WW2, had cost $2.2 billion (about $26 billion in 2015 dollars).

The Manhattan project took less than 4 years, and much of the work took place in vast facilities in Oak Ridge, Tennessee, and Hanford, Washington.

Los Alamos, New Mexico was selected as the site for Project Y, the code name for the main atomic bomb scientific laboratory of the Manhattan Project.  J. Robert Oppenheimer was the director of the Los Alamos National Laboratory and responsible for Project Y that designed the atomic bombs.

The only mailing address for the secret Los Alamos location was a post office box, number 1663, in Santa Fe, New Mexico

Two types of atomic bomb were developed during WW2. A relatively simple gun-type fission weapon was made using uranium-235 and a more complex implosion-type weapon.

The gun-assembled device, saw one piece of fissionable material being fired at another piece to produce the chain reaction and an atomic explosion. Fission is the term given to the process of "splitting" atoms through their bombardment by neutrons.

The implosion device consisted of a plutonium sphere surrounded by high explosives. Plutonium is a heavy metal that does not exist naturally. It is produced as a by-product of the fission process in a nuclear reactor.

Radiation detectors were used as safety measures in the Manhattan Project to measure employees clothing and work areas, etc. Nose swabs were also used to detect the inhalation of plutonium dust.

Los Alamos scientist Harry Daghlian and Physicist Louis Slotin both died of acute radiation poisoning following accidents during "Tickling the dragon's tail" experiments at Los Alamos. "Tickling the dragon's tail" was a coined term for the criticality experiments to determine the amount of fissionable material needed for a sustained chain reaction. The two men suffered days of the ravaging effects of radiation sickness before they died.

Oak Ridge and Hanford were used during the Manhattan Project for the purpose of obtaining sufficient quantities of the isotopes uranium-235 and plutonium-239, that were necessary to produce the fission chain reaction and release the destructive energy of the atomic bomb.

Glenn T. Seaborg and his team, working at the University of California in Berkeley, discovered that plutonium is fissionable on March 28, 1941

Physicist Enrico Fermi supervised the world's first controlled sustained chain reaction in 1942 underneath Stagg Field, the abandoned football stadium at the University of Chicago.

The Quebec Agreement, between the United States and Great Britain, was signed on August 19, 1943. The Quebec Agreement outlined the terms of coordinated development of the nuclear energy and the weapons that employed nuclear energy.

Following the Quebec Agreement a large team of British and Canadian scientists moved to the United States to work on the Manhattan Project.

So many people were involved with the Manhattan Project that a special Counter Intelligence Corps was set up to handle the security issues. Lie detection tests were a normal practice as part of the security screening process.

Despite being an ally during WW2, the Soviet Union launched an all-out espionage effort and a Soviet spy ring was established in the 1940s to uncover the military secrets of the United States and Great Britain.

The most famous 'Atomic Spies' were John Cairncross, Klaus Fuchs, Theodore Hall, Ethel and Julius Rosenberg, George Koval, Lona and Morris Cohen, Harry Gold and David Greenglass

Ironically, many of the scientists involved in making the atomic bomb had defected from Germany

J. Robert Oppenheimer, director of the Manhattan Project, is often called the "father of the atomic bomb"

Following the Trinity test, the code name of the first detonation of a nuclear weapon called 'The Gadget', J. Robert Oppenheimer repeated the famous quote "Now I am become Death, the destroyer of worlds."

Hiroshima was chosen as the target for the first atomic bomb because it was a large port city with an army base. Hiroshima had not been damaged much by earlier bombings during WW2 and the devastation inflicted on the city would show the power of the new atomic weapon.

The initial target for the second atomic bomb on August 9, 1945 was Kokura, but there was too much cloud cover for visual targeting, so the destination was changed to the backup target of Nagasaki

Four different size casings were made for the Atomic bombs and were given the code names of "The Gadget", "Fat Man", "Thin Man" and "Little Boy".

The code names for the bombs were created by Robert Serber, an American physicist, who worked on the Manhattan Project. Serber chose them based on the design shapes of the atomic bombs constructed during the Manhattan Project.

The "Thin Man" was a long, thin device, and the name was taken from the Dashiell Hammett detective novel 'The Thin Man' although it was seen as representing President Roosevelt.

The "Fat Man" bomb was round and fat and named after Sydney Greenstreet's character in movie called 'The Maltese Falcon', although it was seen as representing Winston Churchill.

 "The Gadget" was the code name given to the first atomic bomb ever detonated. The term "Gadget" was a laboratory euphemism for a bomb. The Manhattan Project atomic test, code name Trinity, was conducted on July 16, 1945 by the US Army on an isolated mesa at Alamogordo, New Mexico.

The "Gadget" was detonated and monitoring of the explosion took place in bunkers 10,000 yards (9 km) away occupied by scientists and a few dignitaries.

The atomic bomb explosion came as an intense light flash, a sudden wave of heat, followed by a tremendous roar as the shock wave passed and echoed in the valley. A ball of fire rose rapidly, followed by a mushroom cloud extending to 40,000 feet (12,200 metres). Much of the surrounding test area for the bomb was vaporized.

The "Gadget" atomic bomb exploded with a 18,000 ton TNT equivalent and the explosion created a crater which measured nearly 2,400 feet across.  The "Gadget" was an experimental test version of the implosion system used in "Fat Man"

The "Thin Man" was a proposed plutonium gun-type nuclear bomb. Thin Man was 17 feet (5.2 m) long, with a 38-inch (97 cm) wide tail, and a 23-inch (58 cm) mid section. Scientists abandoned the "Thin Man" as the gun-type bomb using plutonium was found to be impractical. It was replaced by the smaller "Little Boy" bomb.

The "Little Boy" atomic bomb was a development of the unsuccessful "Thin Man" nuclear bomb, gun-type fission weapon, using uranium rather than plutonium. The "Little Boy" codename was chosen because of its relationship to the "Thin Man".

The "Little Boy" bomb was 10 feet (3.0 m) long and 28 inches (71 cm) wide. The Little Boy atomic bomb was the first nuclear weapon to be dropped on Japan, targeting Hiroshima on August 6, 1945. Arming of the "Little Boy" bomb began eight minutes into the flight and took 25 minutes.

The "Fat Man" atomic bomb was the implosion model plutonium bomb, the second a-bomb on Japan, that was dropped on Nagasaki on August 9, 1945. It was 10.6 feet (3.3 m) long and 5 feet (1.5 m) wide. The Nagasaki "Fat Man" bomb was made from plutonium, which was even more powerful than uranium.

Project Alberta, also known as Project A, was a section of the Manhattan Project that prepared for the delivery of atomic weapons during combat by conducting weapons delivery tests and modifying aircraft for carrying the atomic weapons developed by the Manhattan Project.

The B-29 Super-fortress bomber was remodeled to deliver the Atomic bomb in the Manhattan Project. The organization and training of flight crews and field teams for weapons handling was an important element of Project Alberta. Colonel Paul Tibbets and the 393rd Bombardment Squadron begin test drops with dummy bombs called "Pumpkins".

Colonel Paul Tibbets and the 393rd Bombardment Squadron begin test drops with dummy bombs called "Pumpkins". The "pumpkins" were mustard colored and were of the approximate size and weight of the "Fat Man" bomb.

The Enola Gay was the name was painted on the Boeing B-29 Superfortress bomber that became the first aircraft to drop an atomic bomb. The Enola Gay dropped the atomic bomb, code-named "Little Boy" on the city of Hiroshima, Japan on August 6, 1945. The aircraft was named for Enola Gay Tibbets, the mother of the pilot, Colonel Paul Tibbets.

Bockscar was the name given to the B-29 Superfortress that dropped the second atomic bomb, "Fat Boy", on the Japanese city of Nagasaki on August 9, 1945. The "Fat Boy" plutonium bomb did not require arming in flight

60,000 people were killed instantly at Hiroshima, and another 200,000 subsequently died as a result of burn and radiation injuries. The atomic bomb dropped at Nagasaki missed its actual target by over a mile. The bomb killed or injured more than 65,000 people and destroyed half of the city.

The Manhattan Project changed the entire way warfare would be fought forever.