Exam Weight

8–10%

What You Will Learn

In this unit, you will study how global power shifted in the early 20th century and how industrialized warfare reshaped the world.

You will begin by examining how imperial rivalries, nationalism, militarism, and alliances destabilized Europe and contributed to World War I (Topic 7.1 & 7.2). You will analyze how new military technologies—such as machine guns, chemical weapons, submarines, and airplanes—transformed warfare and increased the scale of destruction (Topic 7.3).

Next, you will explore how the global economy was disrupted by World War I and how the Great Depression created widespread instability, leading governments to experiment with new economic policies and authoritarian rule (Topic 7.4). You will examine how unresolved tensions from World War I—including the Treaty of Versailles, nationalist movements, and economic hardship—set the stage for World War II (Topic 7.5 & 7.6).

You will then analyze how World War II became a total war involving entire societies, mass mobilization, and unprecedented destruction (Topic 7.7). Finally, you will evaluate how genocides and mass atrocities—including the Holocaust and other state-sponsored violence—reflected extreme nationalist and ideological beliefs (Topic 7.8).

By the end of this unit, you will be able to explain how global conflict reshaped political systems, economic structures, and societies worldwide—and how the consequences of these wars set the stage for the Cold War (Topic 7.9 – causation).

Skills You Will Practice (AP Exam Focus)

Explaining multiple causes of major global conflicts

Analyzing how economic crises contributed to political extremism

Comparing World War I and World War II

Evaluating short-term and long-term effects of global war

Writing complex arguments about causation and historical significance

Strengthening DBQ writing using evidence about total war and ideology

Why This Unit Matters

Unit 7 explains how the 20th century became defined by global war. The destruction of empires, the rise of new ideologies such as fascism and communism, and the redrawing of political borders reshaped the international order.

Many modern institutions, conflicts, and global tensions can be traced back to this era. The United Nations, the Cold War, the rise of the United States and the Soviet Union as superpowers, and ongoing debates about genocide and human rights all emerged from this period of global conflict.

On the AP Exam, this unit requires you to move beyond memorizing events. You must be able to explain why wars broke out, how governments mobilized societies, and what consequences mattered most in the long run.

By the end of this unit, you should be able to clearly explain how industrialized warfare transformed global power—and how the aftermath of these conflicts shaped the modern world.