History of North America

What brought America into WW1?

The Zimmermann Telegram was the primary factor that brought the United States into World War I. This secret telegram, sent by the German Foreign Secretary Arthur Zimmermann to the German ambassador in Mexico, proposed an alliance between Germany and Mexico against the United States.

If the United States declared war on Germany, Mexico would recapture the territories it lost to the United States in the Mexican-American War (1846–1848). The British intercepted and decoded the telegram and shared it with the United States government.

Publication of the telegram in early March 1917 provoked widespread outrage and anti-German sentiment in the United States. It contributed significantly to the decision of the U.S. government to declare war on Germany on April 6, 1917.