-
Scientist Leo Szilard writes a letter to President FDR urging him to support and fund research in regards to nuclear fission as a defense towards Nazi Germany, and Albert Einstein signs the letter as well.
-
Great Britain and France declare war on Nazi Germany, and World War II officially starts.
-
After FDR read the letter from Szilard and other scientists, he created the Advisory Committee on Uranium, which was basically the beginning of the Manhattan Project. However, in June of 1940 this committee becomes a part of the National Defense Research Committee created by FDR.
-
Pearl Harbor is attacked by the Japanese and within the next few days the US has declared war on Japan, Germany, and Italy, officially joining WWII.
-
FDR officially approves the production and further research of an atomic bomb.
-
By showing that a nuclear chain reaction (with uranium) can be sustainable, the possibility of using that sustained reaction in a reactor or bomb became a reality.
-
FDR and Winston Churchill sign the Quebec Agreement, which outlined the terms of how nuclear weapons would be developed
-
200 grams of the rare uranium-235 isotope necessary in manufacturing the bomb are sent to the main assembly plant in Los Alamos, New Mexico
-
Nazi Germany surrenders to the Allied powers which marks the end of World War II in Europe
-
The scientist who has originally been one of the people to tell FDR about the potential of atomic weapons, comes out against the use of them in war.
-
The Trinity Test in Alamogordo, New Mexico becomes the first detonation of an atomic weapon
-
The uranium bomb Little Boy is detonated over Hiroshima, Japan, killing tens of thousands instantly.
-
Just three days after the bombing of Hiroshima, the second atomic bomb named "Fat Man" is dropped on Nagasaki, Japan
-
