It all started in 1938 when three scientists—Otto Hahn, Lise Meitner and Fritz Strassmann —showed evidence for the discovery of nuclear fission by splitting the uranium atom. The discovery was momentous, indeed dangerous, and full of promise, as was said in the Nobel Prize presentation speech for Hahn for his discovery.
In 1939, German scientist Albert Einstein wrote to then US president Franklin Roosevelt that the Nazis were working on an atom bomb, and so in 1941, the US government launched the Manhattan Project, involving thousands of renowned scientists, members of industry, military and many workers, to build the first atomic bombs.Led by Italian scientist Enrico Fermi, the first nuclear reactor was built in 1942 in Chicago and then reactors in Washington, which were used to produce plutonium for nuclear weapons.
On 6 August 1945, the US dropped an atomic bomb on the city of Hiroshima and three days later in Nagasaki. By the end of the year, at least 200,000 people had been killed in the Japanese cities, which became the symbols of nuclear destruction for years to come.