Nuclear History: World War II
The U.S. races to beat Germany to an atomic bomb.
War begins in Europe
The U.S. starts researching uranium
Albert Einstein wrote to President Roosevelt to warn him of a rumored Nazi program to develop nuclear weapons. In response, Roosevelt formed a committee to analyze the state of scientific research on uranium.
Japan bombs Pearl Harbor.
The U.S. declares war on Japan.
Roosevelt Approves Production of the Atomic Bomb
President Roosevelt gave Vannevar Bush, director of the U.S. government’s research into fission, approval to move the project into production. He did so with seven letters: “V.B. OK FDR"
The Manhattan Project Begins
The Manhattan Project brought together the best physicists and engineers in the country to build the most devastating bombs ever imagined. By the program’s end, 130,000 people were employed at more than 30 sites across the U.S., the U.K., and Canada—and two atomic bombs had been dropped on Japan.
The Science of the Bomb
The war ends in Europe. It continues in the Pacific.
The Trinity Test
The Trinity Test in southern New Mexico was the first ever detonation of a nuclear weapon. The bomb exploded with the power of 20 kilotons of TNT. The fireball was 600 feet wide; its heat was felt over 100 miles away.
Manhattan Project scientists petition President Truman not to use the bomb
The Bomb is Dropped on Hiroshima
The bomb codenamed “Little Boy” exploded with the force of 15 kilotons of TNT and killed roughly 135,000 people.
The Soviets declare war on Japan and invade Japanese-occupied territory in China.
The bomb is dropped on Nagasaki
The bomb dropped on Nagasaki was called “Fat Man.” An estimated 40,000 people died from the explosion which was equivalent to 20 kilotons of TNT, and twice as many died from related health issues in the following months and years.