Explore how events between 1900 and 1945 continue to shape today's world.

Essential Events Between 1900 and 1945

Learn how two world wars and other critical developments reshaped global affairs in the first half of the twentieth century.

Timeline timeline

How Do Countries Decide Whether to Go to War?

Learn how balances and imbalances of power contributed to World Wars I and II.

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Why Did World War I Happen?

Explore the causes of the Great War and the ways in which the conflict reshaped society.

Infographic infographic

Why Did World War II Happen?

Understand the issues that drove countries back to battle just two decades after World War I.

Infographic infographic

What Is Fascism?

Learn how Benito Mussolini and Adolf Hitler rose to power and the lessons their political journeys hold for today.

Interactive interactive

How Did the United States Become a Global Power?

Learn about the three wars that transformed the United States’ standing in the world.

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What Are the Origins of Communism?

Explore the different ways Marx, Lenin, and Stalin interpreted communism and dive into the history of translating an ideology into policy.

Interactive interactive

World at War Module Assessment

Questions to check your understanding.

Interactive interactive