The United States declares war on Germany.

On April 6, 1917, the United States formally declared war on Germany, marking its entry into World War I. This decision was prompted by several factors, most notably Germany’s resumption of unrestricted submarine warfare, which threatened American commercial shipping and resulted in the sinking of ships with American passengers, such as the RMS Lusitania in 1915. Additionally, the revelation of the Zimmermann Telegram, in which Germany proposed a military alliance with Mexico against the United States, further inflamed public opinion and solidified support for war. President Woodrow Wilson, who had previously advocated for neutrality, delivered a powerful speech to Congress emphasizing the need to make the world “safe for democracy.” The declaration of war marked a turning point in the conflict, as the mobilization of American troops and resources contributed significantly to the eventual defeat of the Central Powers.