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James Chadwick proves existence of neutrons
James Chadwick proves the existence of neutrons. Not being repelled by similarly-charged particles, the neutron made an ideal "bullet" for bombarding other nuclei. -
The idea of the atomic bomb
Leo Szilard, within seven months of the discovery of the neutron,and more than six years before the discovery of fission, conceived of the possibility of a controlled release of atomic power through a multiplying neutron chain reaction, and also realized that if such a reaction could be found, then a bomb could be built using it. -
Uranium nuclear fission
Otto Hahn, Fritz Strassman and Lise Meitner produce Uranium nuclear fission at Germany's Kaiser Wilhelm Institute. -
Albert Einstein wrote to FDR about a possible atomic bomb
On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told Roosevelt of efforts in Nazi Germany to purify uranium-235, which could be used to build an atomic bomb. The United States Government began the serious undertaking known then only as "The Manhattan Project." -
Roosevelt authorized the Manhattan Project
FDR authorizes the Manhattan Engineering District for the purpose of creating an atomic bomb. It was an investment of $2 Billion, which was used to build a full gaseous diffusion. They came up with the name "Manhattan Project" to disguise the forming of the bomb. -
The United States approved money for the Manhattan Project
The United States Government committed $2 billion dollars to the Manhattan Project to build a secret bomb. At that time, only a few scientists around the globe believed it was theoretically possible. In four short years it became a reality and was a significant factor in bringing an end to World War II. -
Attack on Pearl Harbor
Just before 8 in the morning hundreds of Japanese fighter planes attacked the American naval base at Pearl Harbor near Honolulu, Hawaii. The barrage lasted just two hours, but it was devastating: The Japanese destroyed nearly 20 American naval vessels, including eight enormous battleships, and almost 200 airplanes. After the assault, FDR declared war on Japan, this introduced the US in to WWII. -
First nuclear weapon tested
The first nuclear weapon was detonated as a test by the United States at the Trinity site, exploded at Los Alamos, with a yield approximately equivalent to 20 kilotons. -
Truman orders bombs to be used
Truman held knowledge of the bomb being formed, the ability to end the war was in his hands, but it involved exposing the worst weapon known to man. The decision to drop the Atomic Bomb came about because of the Japanese Leaders rejected the Postdam Declaration. -
First bomb "Little Boy" dropped on Hiroshima
The mushroom cloud billowing up 20,000 feet over Hiroshima. It was the first nuclear weapon to be used and developed by Manhattan Project during WWII. -
Second bomb "Fat Man" dropped Nagasaki
The second nuclear weapon to be used. It was dropped on Nagasaki. It was 10,213 pounds, 10.7 feet long, and 5 feet wide. It was round and fat, that is how it got its name "Fat Man". -
Japan announces formal surrender
Japanese representatives signed the official Instrument of Surrender, prepared by the War Department and approved by President Truman. It set out in eight short paragraphs the complete capitulation of Japan. The opening words, "We, acting by command of and in behalf of the Emperor of Japan," signified the importance attached to the Emperor's role by the Americans who drafted the document.