Timeline of World War II Events

World War II Events

Adolf Hitler is elected to lead Germany under the National Socialist or Nazi Party.

January 30, 1933

Germany invades Poland.

September 1, 1939

Germany invades the Soviet Union.

June 22, 1941

The Allies invade North Africa.

November 8, 1942

Italy surrenders to Allied forces.

September 8, 1943

Allied forces launch the Normandy invasion.

June 6, 1944

Roosevelt, Churchill, and Soviet Premier Joseph Stalin meet at Yalta.

February 4, 1945 - February 11, 1945

President Roosevelt dies.

April 12, 1945

The German armed forces in Europe surrender to the Allies.

May 7, 1945

The Interim Committee recommends keeping the atomic bomb a secret and using it as soon as possible without warning.

June 6, 1945

Truman, Churchill, and Stalin meet in Potsdam.

July 17, 1945 - August 2, 1945

Truman informs Stalin that the United States has tested a powerful new weapon.

July 24, 1945

The Japanese reject the Potsdam Proclamation.

July 29, 1945

The gun model uranium bomb (Little Boy) is dropped on Hiroshima, Japan.

August 6, 1945

The implosion model plutonium bomb (Fat Man) is dropped on Nagasaki, Japan.

August 9, 1945

Japan surrenders.

August 14, 1945

Timeline of Building Atomic Bombs

Scientists flee Europe to escape the rise of Hitler and fascism.

Approx. 1935

Otto Hahn and Fritz Strassmann discover the process of fission in uranium.

December 1938

Eugene Wigner and Leo Szilard went to find Einstein on vacation, urging him to write a letter to Roosevelt about the dangers of Germany’s possible use of nuclear fission research.

July 16, 1939

Albert Einstein writes President Franklin D. Roosevelt, alerting the President to the importance of research on chain reactions and the possibility that research might lead to developing powerful bomb

August 2, 1939

Alexander Sachs discusses Einstein’s letter with President Roosevelt. Roosevelt decides to act and appoints Lyman J. Briggs head of the Advisory Committee on Uranium.

October 11, 1939 - October 12, 1939

Roosevelt informs Einstein that he has set up a committee to study uranium.

October 19, 1939

The Uranium Committee meets for the first time.

October 21, 1939

The Uranium Committee recommends that the government purchase graphite and uranium oxide for fission research.

November 1, 1939

The Uranium Committee receives permission to explore construction needs and cost to build a bomb with the Army.

October 9, 1941

Roosevelt approves production of the atomic bomb.

January 19, 1942

Researchers begin arriving at Los Alamos.

March 1942

Los Alamos, New Mexico is selected as the bomb laboratory. Robert Oppenheimer is chosen as laboratory director.

November 25, 1942

Scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in Chicago.

December 2, 1942

Bomb design work begins at Los Alamos.

April 1943

Bomb models are tested at Los Alamos.

March 1944

A major reorganization to maximize implosion research occurs at Los Alamos.

July 1944

Los Alamos receives it first plutonium.

February 2, 1945

Los Alamos scientists successfully test a plutonium implosion bomb.

July 16, 1945

Truman informs Stalin that the United States has tested a powerful new weapon.

July 24, 1945

The gun model uranium bomb (Little Boy) is dropped on Hiroshima, Japan.

August 6, 1945

The implosion model plutonium bomb (Fat Man) is dropped on Nagasaki, Japan.

August 9, 1945