History Biography Geography Science Games

History >> World War 2 for Kids

World War II

The Atomic Bomb

At the start of World War II in 1939 the atomic bomb had not yet been invented. However, scientists discovered about that time that a powerful explosion might be possible by splitting an atom. This type of bomb could destroy large cities in a single blast and would change warfare forever.

A-bomb mushroom cloud above Nagasaki
The mushroom cloud above Nagasaki, Japan from the atomic bomb
Source: US Government

Albert Einstein

Albert Einstein came up with many of the theories that helped scientists in making the atomic bomb. When he realized that such a bomb could be made, he was frightened about what might happen if Hitler and Germany learned how to make the bomb first. He wrote a letter to US President Franklin Roosevelt telling him about the atom bomb. As a result, Roosevelt set up the Manhattan Project.

Manhattan Project

The Manhattan Project was the name for the research and development program for the atomic bomb. It started small, but as the bomb became more real, the United States added scientists and funding to be sure they were the first to have the bomb. Ironically, many of the scientists involved in making the bomb had defected from Germany. By the end of the project, funding had reached $2 billion and there were around 200,000 people working on the project.

The First Atomic Bomb

On July 16, 1945 the first atomic bomb was exploded in the New Mexico desert. The explosion was massive and the equivalent to 18,000 tons of TNT. Scientists figured that the temperature at the center of the explosion was three times hotter than at the center of the sun.

Although the scientists were happy they had successfully made the bomb, they also were sad and fearful. This bomb would change the world and could cause mass destruction and death. When President Harry Truman heard of the bomb's success he wrote "We have discovered the most terrible bomb in the history of the world".

Deciding to Drop the Bomb

By the time the first atomic bomb had been made, Germany had already surrendered and World War II in Europe was over. Japan was defeated as well, but would not surrender. The US was contemplating an invasion of Japan. Army leaders figured that anywhere from 500,000 to 1 million US and Allied soldiers would die in an invasion. President Truman decided to drop the atomic bomb instead.


On August 6, 1945 an atomic bomb named Little Boy was dropped on Hiroshima, Japan. The explosion was huge, the city was destroyed, and tens of thousands of people were killed. The bomb was dropped by a plane named the Enola Gay which was piloted by Colonel Paul Tibbetts. The bomb itself was over 10 feet long and weighed around 10,000 pounds. A small parachute was on the bomb in order to slow its drop and allow the plane time to fly away from the blast zone.

Little Boy atomic bomb
The Little Boy atomic bomb
Source: National Archives


Despite witnessing the terrible destruction of the bomb on Hiroshima, Emperor Hirohito and Japan still refused to surrender. Three days later, on August 9, 1945, another atomic bomb, nicknamed Fat Man, was dropped on Nagasaki, Japan. Again the devastation was horrible.


Six days after the bombing of Nagasaki, Emperor Hirohito and Japan surrendered to US forces. The Emperor announced this on the radio. It was the first time most Japanese had heard his voice.

Interesting Facts Activities

Take a ten question quiz about this page.

  • Listen to a recorded reading of this page:

  • Learn More about World War II:

    World War II Timeline
    Allied Powers and Leaders
    Axis Powers and Leaders
    Causes of WW2
    War in Europe
    War in the Pacific
    After the War

    Battle of Britain
    Battle of the Atlantic
    Pearl Harbor
    Battle of Stalingrad
    D-Day (Invasion of Normandy)
    Battle of the Bulge
    Battle of Berlin
    Battle of Midway
    Battle of Guadalcanal
    Battle of Iwo Jima

    The Holocaust
    Japanese Internment Camps
    Bataan Death March
    Fireside Chats
    Hiroshima and Nagasaki (Atomic Bomb)
    War Crimes Trials
    Recovery and the Marshall Plan
    Winston Churchill
    Charles de Gaulle
    Franklin D. Roosevelt
    Harry S. Truman
    Dwight D. Eisenhower
    Douglas MacArthur
    George Patton
    Adolf Hitler
    Joseph Stalin
    Benito Mussolini
    Anne Frank
    Eleanor Roosevelt

    The US Home Front
    Women of World War II
    African Americans in WW2
    Spies and Secret Agents
    Aircraft Carriers
    World War II Glossary and Terms

    Works Cited

    History >> World War 2 for Kids

    Ducksters Footer Gif with Ducks

    About Ducksters Privacy Policy 


    This site is a product of TSI (Technological Solutions, Inc.), Copyright 2024, All Rights Reserved. By using this site you agree to the Terms of Use.