What Started World War 2: Timeline

The cause of World War Two is often attributed solely to the invasion of Poland by Germany, which resulted in the deceleration of war by France and Britain.

In this World War 2 timeline, the events leading up to this invasion are explored between 1933 and 1939. We examine these World War 2 dates to better understand the motivations behind this second war. 

Sources such as a 1939 newspaper and more headlines have been collected from multiple newspapers reporting at the time that accurately inform this timeline of events.

Britain Enters the War: 1939-1945

The question of whom or what started WWII cannot be pinpointed to a signal individual or a specific event. The timeline of pre-WW2 events paints a precise picture of the motivations behind the war.

These events likely contributed to the eventual beginning of World War 2. For a more detailed narrative exploring the root causes, then please read What started World War Two post.


  • January 30: President Hindenburg appoints Hitler as chancellor.
  • January to February: Japan conquers the Jehol province in Chinese Manchuria.
  • February 24-25: League of Nations condemns Japan and calls for an end to the Japanese occupation of Manchuria. The Japanese delegation subsequently walks out.
  • March 5: Nazis secure 44% of the vote in Germany’s election.
  • March 23: Enabling Act is passed, which gives dictatorial powers to Hitler.
  • March 27: Japan announces its intention to leave the League of Nations.
  • May 31: Tangku Truce essentially eliminates China’s military presence in northern China and Inner Mongolia.
  • October 14: Germany leaves the League of Nations.


  • October 1: Hitler expands his army and navy, while also ordering the creation of an air force.
  • December 19: Japan refuses to be limited by future naval treaties.
  • December 30: Mussolini begins preparations for an Autumn invasion of Abyssinia.


  • March 7: Saarland restored to Germany.
  • May 2: The Soviet Union and France sign the Mutual Assistance Pact.
  • June 26: The British suggest a compromise to Mussolini over Abyssinia. The Italian rejects it.
  • September 15: Nuremberg Laws passed, which deprived Jews of German citizenship.
  • September 18: The Soviet Union joins the League of Nations.
  • October 3: Italy invades Abyssinia.

what started world war II

Mussolini and Hitler (image source: Wikipedia)


  • January 15: Japan withdraws from the Second London Naval Conference after their request for naval parity with Britain and the USA is refused.
  • February 26-29: Japanese army prevents an attempted coup to reform a civilian government.
  • March 7: Germany reoccupies Rhineland.
  • March 23: Italy, Austria and Hungary sign the Rome Pact.
  • May 9: Italy annexes Abyssinia.
  • July 18: The Spanish Civil War begins, between the Republicans and Franco’s nationalists.
  • October 14: Belgium ends its military alliance with France.
  • November 1: Hitler and Mussolini sign the Berlin-Rome Axis.
  • November 18: Germany and Italy officially recognise Franco’s regime in Spain.
  • November 25: Germany signs the Anti-Comintern Pact with Japan.


  • February 8: In the south of Spain, Franco’s forces take Malaga.
  • April 26: The Axis powers bomb the Basque town of Guernica in Spain.
  • July 7: The Marco Polo Bridge incident outside Peking triggers Japan’s ‘undeclared war’ throughout China.
  • November 25: Italy joins the German-Japanese Anti-Comintern Pact.
  • December 13: Japanese occupy Nanking, committing widespread atrocities on the civilian population in the process.

what started world war 2

Pablo Picasso's "Guernica", 1937 (image source: Wikimedia Commons)


  • March 12: German troops march into Austria, before annexing Hitler’s homeland.
  • April 23: Sudeten Germans in Czechoslovakia demand full autonomy.
  • April (unspecified): Japan’s National Mobilisation Law is passed, resulting in full military mobilisation.
  • September 29: Britain, France and Italy sign the Munich Pact which agreed to transfer Sudetenland to Germany.
  • October 21: Japanese capture Canton.
  • October (unspecified): The Chinese Nationalist government withdraws to Chungking.


  • January 27: Britain and France recognise Franco’s government.
  • March 15: Germany begins its occupation of the rest of Czechoslovakia.
  • March 21: Hitler demands that Poland returns Danzig to Germany.
  • March 23: Germany and the Soviet Union sign the Nazi-Soviet Pact, agreeing to the division of Poland. On the same day, Germany begins its occupation of Memel in Lithuania.
  • April 7: Italy invades Albania.
  • May 22: Germany and Italy agree to a military alliance under the Pact of Steel.
  • May (unspecified): Japan launches long-range bombing raids on Chungking. Japanese troops also clash with their Soviet counterparts in the Nomonhan region.
  • August 23: Germany and the Soviet Union sign the Non-Aggression Pact.
  • August 25: Britain signs the Mutual Assistance Pact with Poland.
  • August-September: Japan is beaten comfortably at Nomonhan, resulting in the Soviet-Japanese armistice on 16 September.
  • September 1: Germany invades Poland.
  • September 3: Britain and France declare war on Germany.

what started world war 2

German troops march through Warsaw, Poland 1939 (image source: Wikimedia Commons)

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world war 2 timeline

Discover the major events between 1933 and 1939 that lead to Germany invading Poland, and the resulting outbreak of one of the worst wars the world would ever see.