The United States entered World War I in April 1917, two and a half years after the war had begun in Europe. There were several factors that led to the U.S. decision to enter the war, including:
- The sinking of the Lusitania. The Lusitania, a British passenger ship, was sunk by a German U-boat in May 1915. The attack resulted in the deaths of over 1,200 people, including 128 Americans. The sinking of the Lusitania was seen as an outrageous violation of international law, and it helped to turn American public opinion against Germany.
- The Zimmerman Telegram. In January 1917, the British intercepted a telegram from the German Foreign Secretary, Arthur Zimmerman, to the German ambassador in Mexico. The telegram proposed an alliance between Germany and Mexico, in which Germany would help Mexico to retake the land that it had lost to the United States in the Mexican-American War. The Zimmerman Telegram infuriated Americans and helped to solidify their support for war against Germany.
- The unrestricted submarine warfare campaign. In early 1917, Germany began an unrestricted submarine warfare campaign, in which German submarines would sink any ship, regardless of its nationality, in the waters around Britain. This campaign caused widespread shipping disruptions and heavy loss of life, including the sinking of several American ships. The unrestricted submarine warfare campaign was the final straw for many Americans, and it helped to push them in favor of war.
The Effects of the U.S. Entry into World War I
The U.S. entry into World War I had a significant impact on the course of the war. Some of the effects of the U.S. entry include:
- The United States provided a massive infusion of manpower and resources for the Allied cause. The U.S. sent over 2 million troops to Europe, and it also provided the Allies with large amounts of money, food, and munitions. This support helped the Allies to turn the tide of the war in their favor.
- The U.S. helped to break the German morale. The arrival of fresh American troops on the Western Front helped to demoralize the German troops, who had been fighting against overwhelming odds for years. The Germans saw the U.S. entry as a sign that the Allies were ultimately going to win the war, and it sapped their will to fight.
- The U.S. helped to accelerate the end of the war. The U.S. military contributed significantly to the Allied victory in World War I. The American troops played a key role in the final Allied offensives of 1918, and they helped to push the Germans back into Germany. The war ended with an armistice on November 11, 1918.
The U.S. entry into World War I had a profound impact on the course of the war and the future of the world. The United States emerged from the war as a major world power, and it would go on to play a leading role in international affairs for decades to come.