Why did the United States enter the First World War, and how did the war reshape the nation at home and its role in the world?
Topics 7.5 and 7.6 World War I, Military, Diplomatic, and Home Front: the reasons for United States entry, the war effort, the fight over the peace, and the war's effects on American society.
A focused answer to AP US History Topics 7.5 and 7.6, covering the First World War: the reasons for United States entry from neutrality to 1917, the home front and the curbing of civil liberties, the Great Migration, Wilson's Fourteen Points, and the Senate's rejection of the Treaty of Versailles.
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What this topic is asking
Topics 7.5 and 7.6 ask you to explain the First World War for the United States: the path from neutrality to entry in 1917, the military and diplomatic effort, the fight over the peace, and the war's effects on the home front, from the curbing of civil liberties to the Great Migration. The exam wants why the United States entered, how the war reshaped society, and why the nation rejected the League of Nations.
From neutrality to war
The home front
The fight over the peace
Wilson sought a lasting peace through his Fourteen Points (1918), a program of self-determination, free trade, freedom of the seas, reduced armaments, and, above all, a League of Nations to keep the peace. At the Paris Peace Conference he won the League but had to compromise on his other goals; the Treaty of Versailles imposed harsh terms on Germany. At home, the Senate, led by Henry Cabot Lodge, balked. Opponents feared that Article X, the collective-security pledge, would commit the United States to fight in future foreign wars without congressional consent. The Senate rejected the treaty in 1919 and 1920, and the United States never joined the League.
The retreat into isolationism
The rejection of the League signaled a broader turn. Disillusioned by the war and its bitter peace, Americans recoiled from foreign entanglement and embraced isolationism through the 1920s. The wartime expansion of government rolled back, civil-liberties crackdowns fed the postwar Red Scare, and the nation turned inward toward prosperity and cultural change. The war had briefly raised the United States to world leadership, but the country declined the role until the crises of the 1930s and the Second World War forced it back onto the global stage.
Worked example: arguing the war changed society
Try this
Q1. Name the German message proposing an alliance with Mexico that helped push the United States into World War I. [Recall]
- Cue. The Zimmermann Telegram, exposed in early 1917.
Q2. Explain why the Senate rejected the Treaty of Versailles. [Short explanation]
- Cue. Many senators, led by Henry Cabot Lodge, feared that Article X of the League of Nations covenant would obligate the United States to defend other member nations and so drag the country into foreign wars without congressional consent; unwilling to surrender that control, the Senate rejected the treaty, and the United States never joined the League.
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 USH (style)3 marksBriefly describe ONE reason the United States entered World War I. Briefly explain ONE effect of the war on the American home front. Briefly explain ONE reason the United States did not join the League of Nations.Show worked answer →
A Short Answer Question (SAQ), 3 points, one per bullet.
A. Describe: German unrestricted submarine warfare, including the sinking of the Lusitania, and the Zimmermann Telegram pushed the United States to declare war in 1917.
B. Home front: the government mobilized the economy and curbed civil liberties, prosecuting dissent under the Espionage and Sedition Acts and fueling the Great Migration of Black Americans north for war work.
C. League: the Senate, led by Henry Cabot Lodge, rejected the Treaty of Versailles over fears that Article X would commit the nation to foreign wars.
Markers want a real cause, a concrete home-front effect, and a genuine reason for rejecting the League.
AP USH (style)6 marksEvaluate the extent to which World War I changed American society in the period 1914 to 1920.Show worked answer →
A Long Essay Question (LEQ), scored on the 6-point rubric.
Thesis (1): "World War I changed American society significantly, expanding federal power over the economy and dissent, accelerating the Great Migration, and briefly raising the nation to world leadership, though the postwar retreat into isolationism limited the lasting change."
Contextualization (1): the European war and America's initial neutrality.
Evidence (2): wartime mobilization and the curbing of civil liberties; the Great Migration and the fight over the League of Nations.
Analysis (2): explain HOW the war transformed government, society, and foreign policy, then add complexity by weighing the swift retreat into isolationism after 1920.
Related dot points
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- Topic 7.1 Contextualizing Period 7: the reform, economic, technological, and global forces that made the United States a modern industrial world power between 1890 and 1945.
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A focused answer to AP US History Topics 7.2 and 7.3, covering American imperialism: the economic, strategic, and ideological causes of expansion, the Spanish-American War of 1898 and the Treaty of Paris, the debate between imperialists and anti-imperialists, and the Open Door policy.
- Topic 7.15 Comparison in Period 7: using the historical reasoning skill of comparison to analyze the developments of the emergence of modern America.
A focused answer to AP US History Topic 7.15, teaching the historical reasoning skill of comparison through Period 7: comparing Progressivism and the New Deal, the two world wars, and the 1920s and 1930s, and how to frame a comparison essay for the DBQ or LEQ.
Sources & how we know this
- AP United States History Course and Exam Description — College Board (2020)