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Topic guide

Second World War

A global conflict of occupation, genocide, resistance and mass mobilisation from 1939 to 1945.

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Overview

The Second World War was a connected series of conflicts fought across Europe, Africa, Asia, the Atlantic and the Pacific between 1939 and 1945. It grew out of unresolved tensions after the First World War, aggressive expansion by Germany, Italy and Japan, the weakness of collective security and decisions made by governments that still had alternatives.

The war was fought by vast coalitions rather than by two simple, unchanging sides. It involved military campaigns, occupation, resistance, strategic bombing, economic mobilisation and mass displacement. Nazi Germany and its collaborators murdered six million European Jews in the Holocaust and persecuted and killed millions of other people.

The Allied victory destroyed the Axis regimes but left much of Europe and Asia devastated. It accelerated decolonisation, strengthened the United States and Soviet Union, helped produce the United Nations and opened the nuclear age.

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The essential guide

01

How the peace after 1918 broke down

The Treaty of Versailles imposed territorial losses, military restrictions and reparations on Germany, but the treaty alone did not make another war inevitable. The Great Depression weakened democratic politics, while Adolf Hitler and the Nazi movement deliberately pursued dictatorship, racial conquest and revision of the European settlement.

Britain and France tried negotiation, deterrence and rearmament in different combinations. Appeasement reflected fear of another catastrophic war, military weakness and genuine grievances about parts of the peace settlement, but the Munich Agreement of 1938 sacrificed Czechoslovakia's borderlands without producing a durable peace.

02

From European crisis to global war

Germany invaded Poland on 1 September 1939. The rapid defeat of Poland was followed in 1940 by German victories in Scandinavia and western Europe. Britain remained in the war after France fell, while fighting spread through the Mediterranean and North Africa.

Germany invaded the Soviet Union in June 1941 in a war of conquest and annihilation. Japan's attack on Pearl Harbor in December brought the United States directly into the conflict. Existing wars in Europe and Asia now formed one global struggle.

03

Turning the military balance

The Soviet victory at Stalingrad, the Allied success in North Africa, the Battle of the Atlantic and American advances after Midway did not end the war at once, but together shifted the strategic initiative. Industrial production, shipping, intelligence and the ability to replace losses were as important as individual battles.

The invasion of Normandy in June 1944 established a western front in France while the Red Army advanced from the east. Germany surrendered in May 1945. In Asia, fighting continued until Japan accepted surrender after the atomic bombings of Hiroshima and Nagasaki and the Soviet declaration of war against Japan.

04

Occupation, genocide and civilian war

Occupation policies differed across territories but commonly involved coercion, forced labour, food seizures and violent reprisals. Nazi racial policy radicalised into the systematic murder of Europe's Jews. Roma and Sinti, disabled people, Soviet prisoners of war, Polish elites, political opponents and others were also targeted.

Civilian populations experienced bombing, hunger, conscription, displacement and family separation. Home fronts expanded state power and drew women into new forms of paid and military work, although wartime mobilisation did not remove older inequalities.

05

Victory and consequences

Victory left difficult questions about borders, refugees, justice and reconstruction. War-crimes trials established important precedents but could not address every crime. Germany and other territories were occupied, while political rivalry between the Western Allies and the Soviet Union hardened into the Cold War.

The conflict's meaning remains debated. Military history explains operations and resources; social and cultural history recovers civilian experience; histories of empire show how colonial troops, labour and resources sustained the war and how wartime promises encouraged demands for independence.

Chronology

Key dates

  1. Treaty of Versailles

    The peace treaty with Germany reshaped borders and imposed military restrictions and reparations.

  2. Hitler became chancellor

    The Nazi seizure of power destroyed German democracy and enabled an expansionist racial dictatorship.

  3. Munich Agreement

    Britain, France, Germany and Italy agreed that Germany could annex the Sudetenland.

  4. Germany invaded Poland

    Britain and France declared war two days later.

  5. Fall of France

    German forces defeated France and the Low Countries.

  6. Operation Barbarossa

    Germany and its allies invaded the Soviet Union.

  7. Pearl Harbor

    Japan attacked the US Pacific Fleet; the United States entered the war.

  8. Second Battle of El Alamein

    The British-led Eighth Army defeated Axis forces in Egypt.

  9. Stalingrad ended

    The remaining German forces in the city surrendered.

  10. D-Day

    Allied forces landed in Normandy.

  11. War ended in Europe

    Victory in Europe Day followed Germany's unconditional surrender.

  12. Japan formally surrendered

    The surrender ceremony in Tokyo Bay marked the war's formal end.

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Questions and debates

Why did the international system fail to contain Axis expansion?

How did industrial capacity, logistics and coalition warfare shape the outcome?

How should military campaigns be studied alongside genocide, occupation and empire?

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Essential stories

Begin with the foundations, then move into the events, people and debates that add detail and complexity.

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People

Winston Churchill1874–1965Franklin D. Roosevelt1882–1945Joseph Stalin1878–1953Dwight D. Eisenhower1890–1969Charles de Gaulle1890–1970Adolf Hitler1889–1945George VI1895–1952Neville Chamberlain1869–1940Harry S. Truman1884–1972J. Robert Oppenheimer1904–1967

Events

Second World War1939–1945D-Day6 June 1944German Invasion of Poland1 September 1939Battle of BritainJuly–October 1940Operation Barbarossa22 June 1941Attack on Pearl Harbor7 December 1941Battle of Stalingrad23 August 1942–2 February 1943Second Battle of El Alamein23 October–11 November 1942Fall of Berlin2 May 1945Atomic Bombing of Hiroshima6 August 1945
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