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US Entry into WWI

Aug 3, 2025

Overview

This lecture discusses the transition of the United States from a position of neutrality to involvement in World War I, focusing on the economic, political, and social factors that influenced this decision.

US Neutrality and Early Attitudes

  • The US population included many recent immigrants with diverse opinions about the war.
  • World War I was in a stalemate when President Wilson declared US neutrality.
  • Wilson argued the war was not America’s concern, but the US had economic interests at stake.

Economic Ties and Trade

  • In 1914, US exports to Allied Powers totaled about $824 million compared to much less with Central Powers.
  • By later years, US trade and loans to Allies rose to $3.2 billion, while only $1.2 million went to Central Powers.
  • Britain’s naval blockade restricted supplies to Germany, reducing US trade with the Central Powers.

German Submarine Warfare

  • Germany used submarines (U-boats) to break the British blockade and attack ships.
  • The Sussex Pledge was a German promise to stop U-boat attacks, but it was not honored.
  • German U-boats declared any ship to Allied ports would be targeted.

The Sinking of the Lusitania

  • On May 7, 1915, a German U-boat sank the British passenger ship Lusitania, killing 1,198, including 128 Americans.
  • Despite public outrage, Wilson did not immediately seek war, still preferring neutrality.

The Zimmerman Telegram

  • In January 1917, Germany sent a secret telegram to Mexico proposing an alliance against the US, promising the return of lost territories.
  • The British intercepted and decoded the message, passing it to the US, increasing anti-German sentiment.

Debating War Entry

  • Pro-war factors: outrage over submarine warfare, pro-Allied sentiment, economic interests, and the Zimmerman Telegram.
  • Anti-war factors: tradition of neutrality, sympathy for Central Powers among some Americans, anti-English sentiment, opposition to alliance with the Russian Czar, and pacifism.

US Declaration of War

  • Renewed German U-boat attacks in early 1917 broke the Sussex Pledge.
  • President Wilson asked Congress to declare war; Congress did so on April 6, 1917, entering the US into World War I.

Key Terms & Definitions

  • Neutrality — Policy of not supporting or assisting either side in a conflict.
  • Stalemate — A situation where neither side can win or make progress.
  • U-boat — German military submarine used in World War I.
  • Sussex Pledge — Germany’s promise to stop unrestricted submarine warfare, later broken.
  • Lusitania — British passenger ship sunk by a German U-boat in 1915.
  • Zimmerman Telegram — Secret German proposal to Mexico to join the war against the US in exchange for lost territory.

Action Items / Next Steps

  • Review the causes for US entry into WWI.
  • Be prepared to discuss the pros and cons of US involvement in the war for next class.