Why did the unresolved tensions of the interwar years erupt into a second world war?
Topic 7.6 Causes of World War II: the causes of the Second World War, including the legacy of the First World War, the Great Depression, fascist and militarist expansion, and the failure of appeasement and collective security.
A focused answer to AP World History Topic 7.6, explaining the causes of the Second World War: the legacy of Versailles and the Great Depression, fascist and militarist expansion by Germany, Italy, and Japan, and the failure of appeasement and the League of Nations.
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What this topic is asking
Topic 7.6 covers the causes of the Second World War. It asks you to explain how the unresolved tensions of the interwar years erupted into a second global conflict: the legacy of the First World War and the Treaty of Versailles, the Great Depression, the aggressive expansion of fascist and militarist regimes in Germany, Italy, and Japan, and the failure of appeasement and collective security to stop them.
What caused the Second World War
The legacy of the First World War and the Depression
The deeper causes lay in the interwar years.
The Treaty of Versailles had bred deep resentment in Germany, which the Nazis exploited (Topic 7.5). The Great Depression brought mass unemployment and despair that discredited democracies and helped extremist movements gain power (Topic 7.4). Together these created the conditions in which aggressive, expansionist regimes could seize power and win support by promising national renewal and revenge.
Fascist and militarist expansion
The immediate cause was aggression.
The failure of appeasement and collective security
The democracies failed to stop the aggressors.
- Appeasement. Britain and France pursued appeasement, giving in to Hitler's demands to avoid war. The Munich Agreement of 1938 handed Germany part of Czechoslovakia in exchange for promises of peace, but it only emboldened Hitler to demand more.
- A powerless League. The League of Nations condemned aggression but could not enforce its decisions; it failed to stop Japan in Manchuria or Italy in Ethiopia.
- The collapse of resistance. By the time the democracies abandoned appeasement, the aggressors had grown strong and confident, and the invasion of Poland finally brought war.
The failure of collective security meant aggression went unchecked until it triggered a second world war.
Try this
Q1. Name the 1938 agreement in which Britain and France handed Germany part of Czechoslovakia to avoid war. [Recall]
- Cue. The Munich Agreement.
Q2. Explain how the failure of appeasement contributed to the Second World War. [Short explanation]
- Cue. By giving in to Hitler's demands rather than resisting, the democracies emboldened him to demand and seize more, so appeasement encouraged further aggression instead of preventing war, which finally came with the invasion of Poland.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2019 (style)3 marksBriefly identify ONE cause of the Second World War. Briefly explain ONE act of fascist or militarist expansion. Briefly explain ONE reason appeasement failed to prevent war.Show worked answer →
A Short Answer Question (SAQ), 3 points, one per bullet.
A. Identify: the resentment and instability left by the First World War and the Great Depression helped bring aggressive regimes to power.
B. Expansion: Germany under Hitler remilitarized and annexed territory, Italy invaded Ethiopia, and Japan invaded Manchuria and then China, defying the postwar order.
C. Appeasement failure: by giving in to Hitler's demands, as at the Munich Agreement over Czechoslovakia, the democracies only encouraged further aggression rather than preventing war.
Each bullet must be concrete.
AP 2022 (style)6 marksEvaluate the most significant cause of the Second World War.Show worked answer →
A Long Essay Question (LEQ), scored on the 6-point causation rubric.
Thesis (1): "The most significant cause of the Second World War was the aggressive expansion of fascist and militarist regimes in Germany, Italy, and Japan, though the legacy of the First World War, the Great Depression, and the failure of appeasement made that expansion possible."
Contextualization (1): situate the war in the unresolved tensions and economic crisis of the interwar years.
Evidence (2): Versailles resentment and the Depression; Nazi, Italian, and Japanese expansion; the Munich Agreement and appeasement; the weak League of Nations.
Analysis (2): explain HOW fascist expansion drove the world to war, then add complexity by weighing it against the deeper causes of postwar grievance, economic crisis, and failed collective security.
Related dot points
- Topic 7.5 Unresolved Tensions After World War I: the political and social tensions left by the peace settlement, including the Treaty of Versailles, the mandate system, anticolonial movements, and the rise of fascism and authoritarianism.
A focused answer to AP World History Topic 7.5, explaining the tensions left after the First World War: the harsh Treaty of Versailles and German resentment, the mandate system and broken promises to colonized peoples, the rise of fascism and authoritarianism, and the weakness of the League of Nations.
- Topic 7.4 Economy in the Interwar Period: the economic crises between the wars, especially the Great Depression, and the varied government responses, including increased state intervention and the rise of authoritarian regimes.
A focused answer to AP World History Topic 7.4, explaining the interwar economy: the Great Depression and its global spread, the varied government responses from the New Deal and Keynesian intervention to Soviet command planning and fascist autarky, and the political consequences.
- Topic 7.7 Conducting World War II: the methods and technologies of the Second World War, including total war, the deliberate targeting of civilians, new weapons, and the use of the atomic bomb.
A focused answer to AP World History Topic 7.7, explaining how the Second World War was fought: total war and total mobilization, new technologies like tanks, aircraft, and radar, the deliberate targeting of civilians through strategic bombing, and the use of the atomic bomb.
- Topic 7.8 Mass Atrocities After 1900: the genocides and mass killings of the twentieth century, including the Holocaust, the Armenian genocide, and others, and the conditions that enabled them.
A focused answer to AP World History Topic 7.8, explaining the mass atrocities and genocides of the twentieth century: the Holocaust, the Armenian genocide, the Holodomor, the Cambodian and Rwandan genocides, and the conditions of ideology, total war, and state power that enabled them.
- Topic 7.9 Causation in Global Conflicts: applying the historical reasoning skill of causation to the global conflicts of the twentieth century, including the world wars and their causes and consequences.
A focused answer to AP World History Topic 7.9, the causation reasoning skill applied to Unit 7: explaining the causes and effects of the world wars, distinguishing long-term from immediate causes, and how to structure a causation essay on twentieth-century conflict.
Sources & how we know this
- AP World History: Modern Course and Exam Description — College Board (2020)