World War II Timeline (1939–1945)

Updated January 12, 2023 | Infoplease Staff
WWII fighter planes
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The second world war, which lasted from 1939 to 1945, was the deadliest conflict in world history. The war began in Europe, but soon expanded to involve North Africa, the Mediterranean region, The Asian Pacific, the Soviet Union, and even some countries in the Americas.

We can still feel the repercussions of the war today, from the rise of Japan as an economic powerhouse to the Cold War to the ongoing Israeli-Palestinian conflict, and more.

We’ll look at the major events of the war in the various theaters in a bit. But first, we’ll answer a few commonly asked questions.

Which Countries Fought in World War II?

More than 30 countries participated in World War II. The major players were divided into two groups: the Allies and the Axis Powers.

Allies vs. Axis

The primary Axis Powers were Germany, Japan, and Italy. This alliance dates to the October 1936 Rome-Berlin Axis laid out in a speech by Benito Mussolini of Italy.

Japan joined the Axis in 1940 with the Tripartite Pact (also called the Berlin Pact). Other countries that would later join the Axis included:

  • Romania
  • Hungary
  • Bulgaria
  • The Independent State of Croatia
  • Slovakia

The Allied Powers came together to oppose the alliance of Nazi Germany, Imperial Japan, and fascist Italy. The countries that formed the original alliance were the United States, the United Kingdom, and the Soviet Union.

A formal agreement in 1942, the United Nations (not to be confused with the United Nations Organization founded in 1945), expanded the Allies to include:

  • China
  • Australia
  • Belgium
  • Canada
  • Costa Rica
  • Cuba
  • Czechoslovakia
  • Dominican Republic
  • El Salvador
  • Greece
  • Guatemala
  • Haiti
  • Honduras
  • British India
  • Luxembourg
  • Netherlands
  • New Zealand
  • Nicaragua
  • Norway
  • Panama
  • Poland
  • South Africa
  • Yugoslavia

What Started WW2?

Unlike World War I, which was sparked by the assassination of Archduke Ferdinand in 1914, the buildup to the second world war was gradual, and included events in many parts of the world.

Most consider the start of the war to be the German invasion of Poland on September 1, 1939. Before this, however, Germany had annexed Austria and the Sudetenland in Czechoslovakia.

As part of a policy of appeasement, Britain and France codified this annexation in the Munich Agreement. In exchange, Adolf Hitler promised no further territorial demands.

When Hitler broke the agreement by invading Poland on September 1, 1939, Britain and France declared war on Germany.

The war, however, was much larger than this. Other events that led to WWII include:

Where Did World War II Take Place?

The second world war had three primary theaters: Europe, the Mediterranean (including North Africa and the Middle East), and the Pacific. Each theater had several fronts:

European Theatre

  • Nordic Front (Scandinavia)
  • Western Front (Western and Central Europe)
  • Eastern Front (Russia and the Soviet Union)

Mediterranean Theatre

  • The Mediterranean
  • North Africa
  • East Africa
  • Gibraltar
  • The Middle East
  • The Balkans
  • Greece
  • The Adriatic Sea
  • Malta
  • Yugoslavia and the Balkans
  • Dodecanese Islands

Pacific Theatre

  • Japan
  • China
  • Burma
  • India
  • Manchuria
  • The Philippines
  • South Pacific islands

Why Was World War II so Important?

Why does the second world war loom so large in our collective memory? There are many reasons. Here are just a few.

The Deadliest Conflict in World History

World War II directly involved some 100 million people from 30 different countries and was the first and only time one country used a nuclear weapon against another.

It Changed the Face of Global Relations

After the war, countries established several organizations with the goals of helping the world to recover from the conflict and preventing future conflict. These include:

The Geneva Convention treaties and the establishment of the International Court of Justice also came in the aftermath of the second world war.

It Set the Stage for Subsequent Conflicts

The genocide of six million Jews in the Holocaust led to the partitioning of the Arab state of Palestine to establish the modern state of Israel. Arab countries’ rejection of the United Nations Partition Plan for Palestine led to decades of war in the region.

The second world war also set the stage for the Cold War, which pitted the United States against the Soviet Union in a decades-long race for influence and nuclear superiority.

The Chinese Civil War between the Chinese Communist Party (CCP) and the Kuomintang (Chinese Nationalist Party) paused during the second world war. After the war, it resumed, and the Chinese Communist Party emerged victorious.

The division of Korea in 1945 into the Soviet-supported communist North Korea and American-supported democratic South Korea set the stage for the Korean War (1950-1953). This was an exceptionally deadly war, with three million civilian casualties. Korea remains divided to this day.

The Race for Nuclear Armament & Disarmament

After the United States dropped nuclear bombs on Hiroshima and Nagasaki, demonstrating the weapons’ devastating power, countries around the world raced to develop their own nuclear arsenal. At the same time, a worldwide peace and disarmament campaign developed.

WW2 Timeline of Events

The major events of the war, as they happened. For detailed timelines in each theatre, please see our articles on the European Theatre, the Mediterranean Theatre, and the Pacific Theatre.

World War II Timeline (1939-1945)

1939

September 1

September 3

  • Britain and France declare war on Germany.

September 3

  • Britain and France declare war on Germany.

September 1939 to September 1945

  • The battle between Allied forces and Japanese forces in the Pacific is ongoing.

November 30, 1939, to March 13, 1940

  • The Winter War between Finland and the Soviet Union.

1940

March 18

  • Hitler and Italian leader Benito Mussolini meet at the Brenner Pass. Mussolini agrees to enter the war at a future date.

March 30

  • Japan establishes a puppet government in Nanking, China.

April 9

  • Germany successfully invades Norway and Denmark.

May 1940 to May 1945

  • The North African campaign. Allied and Axis forces battle across North and East Africa.

May 10

  • The Nazis invade France, the Netherlands, Belgium, and Luxembourg. British Prime Minister Neville Chamberlain, who championed the appeasement of Hitler before the invasion of Poland, resigns. Winston Churchill becomes Prime Minister.

May 12

  • German forces invade France using “Blitzkrieg” tactics.

May 26 to June 3

  • British civilian and naval craft rescued between 335,000 and 400,000 Allied soldiers from Belgium in the Dunkirk Evacuation.

June 10

  • Italy declares war on France and Britain then invades France. The Mediterranean theater opens (including North Africa and the Middle East).

June 14

  • German forces enter Paris.

June 22

  • France and Germany sign an armistice at Compiègne. France and Italy sign an armistice on the 24th.

June 25

  • France officially surrenders to Germany.

July 10 to October 31

  • The Battle of Britain. Germany carries out bombing raids over Great Britain. The Royal Air Force fends them off. Germany’s defeat in this battle is considered one of the turning points of the war.

July 18 to September 4

  • Japanese diplomat Chiune Sugihara writes thousands of travel visas granting Jews safe passage from Russia to Japan. Working 18 to 20 hours per day, Sugihara is credited with saving as many as 6,000 lives.

August 4

  • Italian forces occupy British Somaliland in North Africa.

September 7, 1940, to 31 March 1941

  • The Blitz. Germany carries out nighttime bombing raids over the United Kingdom.

September 27

  • Germany, Italy, and Japan sign the Tripartite Act, agreeing to mutual aid. The name “Axis Powers” emerges.

October 15

  • Italy invades Greece.

October 19-20

  • Italy bombs Bahrain and American-owned oil refineries in Egypt.

October 24

  • Hitler meets with French Prime Minister Philippe Petain, who agrees to collaborate with the Nazis.

October 28

  • The Greco-Italian War begins, opening the Balkan Front. This war will last until April 23, 1941, when Germany invades and occupies Greece (the Battle of Greece).

October and November

  • Soviet Foreign Minister Vyacheslav Molotov, Adolf Hitler, and German Foreign Minister Joachim von Ribbentrop meet to discuss the possibility of the Soviet Union joining the Axis powers. The talks deteriorate, and Hitler plans Operation Barbarossa, to invade of the Soviet Union.

November

  • Hungary, Slovakia, and Romania join the Tripartite Pact.

December 6-9

  • British forces launch Operation Compass, attacking Italian forces in North Africa.

1941

March 1

  • Bulgaria joins the Tripartite Pact.

    Hitler orders the expansion of the Auschwitz-Birkenau concentration camp.

    Rommel sends the Afrika Corps to North Africa to counter Allied gains there.

April 6

  • German, Italian, and Hungarian forces attack Greece and Yugoslavia.

April 11

  • Though still officially neutral, the United States begins sea patrols in the North Atlantic.

April 13

  • Japan and the Soviet Union sign a neutrality pact.

April 17

  • Yugoslavia surrendered to Germany.

April 27

  • Greece surrenders to Germany.

May 2

  • Britain invades pro-Axis Iraq, and the Anglo-Iraqi War begins. The war ends on May 31, when the pro-Axis government surrendered.

June 2

  • The Tuskegee Airmen, the first African American military pilots, began, with the formation of the 99th Fighter Squadron.

June 21

June 22

  • Hitler invades the Soviet Union, opening up the Eastern Front. The attack took place over a 2,900-kilometer (1,800 mi) stretch of land. The Eastern Front would see some of the worst atrocities and highest casualties of the war.

    Germany’s invasion was ultimately unsuccessful and marked a turning point in the war.

July 2

  • The Ponary Massacre, in which the German SS and SD murdered some 100,000 Russians, Poles, and Jews. There would be many, many more massacres at this site.

July 4

  • Mass murder of Polish scientists and writers in Lwow, Poland.

July 8

  • Britain and the Soviet Union sign a mutual defense agreement.

July 26

  • In the United States, President Roosevelt orders the seizure of all Japanese assets.

July 31

  • Hermann Goehring instructs SS Chief Reinhard Heydrich to carry out the “Final Solution” to the Jewish question. By this point, Jews and others have been subject to state-sanctioned persecution and violence for over eight years (see our timeline of the Holocaust).

August 14

  • American President Frederick D. Roosevelt and British Prime Minister Churchill sign the Atlantic Charter, agreeing on postwar peace goals.

September 8

  • Germany’s siege of Leningrad begins. At its height, 3,000 people per day will die.

December 7

  • Japan attacks Pearl Harbor, crippling the U.S. Pacific fleet. Japan also attacks the Philippines and Guam. The United States enters the war.

December 9

  • China declares war on Japan, Germany, and Italy. Both Australia and South Africa declare war on Japan.

December 11

  • The US and Britain declare war on Japan.

    Germany and Italy declare war on the US.

    The US declares war on Germany and Italy.

1942

January

  • Operation Barbarossa is declared a failure. Germany retreats from Russia.

February 25, 1942, to March 20, 1946

  • Japanese Americans are interned in concentration camps in the western United States.

April 9

  • U.S. forces on the Bataan peninsula in the Philippines surrendered to the Japanese.

May 6

  • U.S. and Filipino troops on Corregidor island in Manila Bay surrender to the Japanese. 

June 4 to 7

  • American forces defeat Japanese forces at the Battle of Midway, a turning point in the war.

July 1 to 27

  • The first Battle of El Alamein was between Allied and Axis forces in Egypt. The battle ended in a stalemate but kept the Germans from capturing the Suez Canal.

August 7

  • U.S. Marines land on Guadalcanal Island, where a Japanese air base is threatening Australia.

August 23 to February 2, 1943

  • The Soviet Union defeats Germany in the Battle of Stalingrad. With more than two million casualties, this was one of the bloodiest battles in human history. The victory was a turning point, energizing Soviet forces, and forcing the Germans to retreat.

1943

January 14 to 24

  • The Casablanca Conference. Churchill and Roosevelt agree that the goal should be the unconditional surrender of the Axis powers.

January to April

  • Jews in the Warsaw Ghetto rise up against the Nazis several times, beginning on January 18. The ghetto is exterminated in May.

January 25

  • The US Army XIV Corps lands in the Pacific Theatre.

January 27

  • The first All-American bombing raid on Germany.

February 2

  • The German Army surrendered at Stalingrad. This is a turning point in the war with Russia.

February 9

  • American forces secure Guadalcanal.

March 12

  • Nazi-occupied Karditsa, Greece, is liberated by Allied forces. This is the first city to be liberated.

March 16

  • The first reports of the Katyn Massacre of some 20,000 prisoners of war by the Russian NKVD.

April 4

  • American and Filipino prisoners of war escaped from the Japanese on Mindanao Island. They bring the first news of the Bataan Death March and other atrocities committed by the Japanese.

April 19 to 30

  • The Bermuda Conference. The US and UK leadership discuss the plight of the European Jews.

April 19 to 30

  • The Bermuda Conference. The US and UK leadership discuss the plight of the European Jews.

April 25

  • Mussolini is deposed. Badoglio is named premier of Italy. 

May 9

  • The Changjiao Massacre. Japanese forces murder 30,000 Chinese civilians.

July 5

  • Operation Citadel (the Battle of Kursk) begins. This land battle between the Soviet Union and Germany would become the largest tank battle in history.

July 10

  • Operation Husky, the Allied invasion of Sicily, begins.

August 19

  • Roosevelt and Churchill sign the Quebec Agreement, outlining the terms for the coordinated development of nuclear energy and weapons.

September 3

  • Italy signs a secret armistice and drops out of the war. British troops arrive in Italy. A battle between Germany and the Allied forces will continue in Italy.

September 28 to October 1

  • The people of Naples rise up against the Nazi occupiers. Ultimately, they are successful.

October 10

  • Chiang Kai-shek is sworn in as Chairman of the Nationalist Government of China.

October 18 to November 11

  • The Moscow Conference. The United States, the United Kingdom, and the Soviet Union meet in Moscow to discuss the war. Four declarations came out of the meetings: The Declaration on Italy, the Declaration on Austria, the Declaration on Atrocities, and the Four Nations Declaration, which China was invited to sign. The European Advisory Commission was also formed.

November 10

  • The Cairo Conference. Roosevelt, Churchill, and Chiang Kai-shek pledge to defeat Japan and free Korea.

November 28 to December 1

  • The Tehran Conference. FDR, Churchill, and Stalin agreed on plans to invade Europe (Operation Overlord)

1944

January 24

  • The 872-day Siege of Leningrad ends with Germany withdrawing. Some two million people have died from starvation and disease.

March 7 to May 31

  • Japanese forces invade India at Imphal. The effort will ultimately fail.

March 21

  • Finland rejects the terms of a Soviet peace offer.

May 8

  • A date is set for D-Day (Operation Overlord): June 5.

June 2

  • A provisional French government is established.

June 4

  • The Allies take Rome. D-Day is postponed by 24 hours due to the high seas.

June 6

  • D-Day commences with the Allied bombing of German gun positions at Normandy. Then Allied troops land on the beaches of Normandy. This is the largest amphibious military attack in history.

June 9

  • Soviet forces attack Finland on the way to Berlin.

June 13

  • Germany attacks England with its V1 Flying Bomb (an early cruise-type missile). The V1 attacks will continue, causing great damage.

July 20

  • The July 20 Plot to assassinate Hitler. It is unsuccessful.

July 24

  • Soviet troops liberate the Majdanek concentration camp. This is the first camp liberation.

August 21

  • The Dumbarton Oaks Conference in Washington, DC, set out the basic structure for the United Nations.

August 25

  • Paris is liberated by Allied troops. On August 31, the forces hand over control of France to the Free French Troops.

September 2

  • Allied troops enter Belgium. British forces will liberate Brussels on September 3.

September 4

  • A cease-fire between Finland and the Soviet Union. They will sign an armistice on September 19.

September 12

  • The Second Quebec Conference. Roosevelt and Churchill discuss the future of Germany and cooperation in the Pacific.

September 30

  • The German garrison at Calais surrendered to Canadian forces. Calais is an important crossing point between Europe and Britain.

October 7

  • The Sonderkommando Uprising at Auschwitz. Sonderkommando (prisoner collaborators) revolt when it’s discovered that they, too, are slated for extermination. 450 are killed in the uprising.

October 9

  • The Moscow Conference (1944). Stalin and Churchill discuss postwar spheres of influence.

October 23-26

  • The Battle of Leyte Gulf. The US wins a decisive battle against Imperial Japan in the Philippines. This is considered the largest naval battle in history.

December 16

  • The Battle of the Bulge. Germans launch an offensive against the Allies in Belgium, hoping to take the port of Antwerp. This was the last Axis offensive on the Western Front and marked the beginning of Germany’s retreat.

1945

February 11

  • The Yalta Agreement was signed by Roosevelt, Churchill, and Stalin. The agreement established the basis for the occupation of Germany and returned lands to the Soviet Union taken by Germany and Japan. The USSR agrees to a friendship pact with China.

February 19 to March 26

  • American forces defeat Japanese forces at the Battle of Iwo Jima.

April 28

  • Mussolini is killed at Lake Como.

May 1

  • Hitler’s suicide is announced.

May 2

  • Berlin falls to Allied forces.

May 8

  • The Allies declare V-E (Victory in Europe) Day.

July 17 to August 2

  • The Potsdam Conference. American President Truman, Churchill, British Prime Minister Clement Atlee, and Stalin establish a council of foreign ministers to prepare peace treaties and plan German postwar government and reparations.

August 6

  • The United States drops an atomic bomb on Hiroshima.

August 8

  • USSR declares war on Japan.

August 9

  • The United States drops an atomic bomb on Nagasaki.

August 14

  • Japan agrees to surrender.

September 2

  • V-J Day, or Victory in Japan Day. Japan signs a surrender agreement aboard the US battleship Missouri. This is considered the end of the war.

How Did World War II End?

In April 1945, Soviet troops captured Berlin. On April 29, German troops in Italy surrendered to the Allies, and on April 30, Soviet troops captured the Reichstag. The capture of the Reichstag is considered to signify the military defeat of Germany.

The German garrison in Berlin surrendered on May 2, 1945.

On August 6 and 9, 1945, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki, respectively. Between the bombings, the Soviet Red Army captured strategic Asian targets.

Japan surrendered to the Allies on August 15, 1945, ending the war in the Pacific theatre. And Emperor Hirohito’s signing of the surrender documents on September 2, 1945, is considered to be the end of the Second World War.

What Happened in World War II?

The second world war was the deadliest in history. It set the stage for many of today’s conflicts but also resulted in the establishment of many of the institutions that safeguard peace and human rights around the world.

How much do you know about the Second World War? Test your knowledge with our WWII quiz or Holocaust quiz to find out!

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