9. The United States Declares War on Germany
In April 1917, the United States declared war on Germany, marking a pivotal shift in World War I. President Woodrow Wilson cited Germany’s resumption of unrestricted submarine warfare, which had led to the sinking of American merchant ships, and the interception of the Zimmermann Telegram, which proposed a German-Mexican alliance against the U.S. This decision provided the Allies with substantial financial, industrial, and military resources, significantly altering the conflict’s dynamics. (history.com)
