ID: Unrestricted Submarine Warfare
When: 1915-1917 (escalated significantly after the sinking of the Lusitania)
Who:
- Germany: The Imperial German Navy, specifically its U-boat fleet.
- United States: President Woodrow Wilson and the American people (indirectly involved as victims).
What:
Germany’s policy of unrestricted submarine warfare during World War I involved attacking any and all ships, including neutral vessels, in the waters around Great Britain. This was a departure from earlier, more restricted forms of submarine warfare. The goal was to cut off supplies to Britain and force it to surrender.
Impact: Why Significant?:
- Lusitania Sinking (May 7, 1915): The sinking of the British passenger liner Lusitania, which carried American citizens, galvanized American public opinion against Germany. While not the sole cause, it greatly intensified anti-German sentiment.
- Zimmermann Telegram (1917): Intercepted by the British, this telegram revealed a German proposal to Mexico to ally against the U.S., further fueling American anger and pushing the U.S. closer to war.
- Declaration of War (April 6, 1917): Germany’s resumption of unrestricted submarine warfare in early 1917, after initially suspending it in response to American protests, proved to be the final straw. It led directly to President Wilson’s request for a declaration of war against Germany, bringing the United States into World War I.
- Shift in War’s Balance: The entry of the United States dramatically altered the balance of power in favor of the Allies, providing vital manpower, resources, and financial support.
- Long-Term Consequences: The war and its aftermath profoundly affected American foreign policy, leading to increased involvement in international affairs and shaping the nation’s role in the 20th century.