What was the specific attack on America that caused it to enter WW1?


America's policy of isolation, and thus wanting stay out of any European affairs while also trying to broker a peace resulted in tensions with both Berlin and London. When a German U-boat sank the British liner Lusitania in 1915, a large passenger liner with 128 Americans also aboard, the United States President, Wilson, vowed "America was too proud to fight", and demanded an end to attacks on passenger ships. Germany complied. Wilson tried to mediate a compromise settlement; yet no compromise was discovered. Wilson also repeatedly warned that America would not tolerate unrestricted submarine warfare because it violated America's rights. Wilson was under great pressure from former president Teddy Roosevelt, who denounced German "piracy" and Wilson's cowardice. In January 1917, the Germans announced they would resume unrestricted submarine warfare. Berlin's proposal to Mexico to join the war as Germany's ally against the U.S. was exposed in February [The Zimmerman Telegram authorized the ambassador to offer Mexico the portions of the Southwest it had lost to the United States in the 1840s if it joined the Central Powers. But because Wilson had run for reelection in 1916 on a very popular promise to keep the United States out of the European war, he had to handle the telegram very carefully. Wilson did not publicize it at first, only releasing the message to the press in March after weeks of German attacks on American ships had turned public sentiment toward joining the Allies.] angering American opinion. After German submarines attacked several American merchant ships, sinking three, Wilson requested that Congress declare war on Germany, which it did on April 6, 1917. The U.S. House of Representatives approved the war resolution 373-50, the U.S. Senate 82-6, with opposition coming especially from German American districts such as Wisconsin. The U.S. declared war on Austria-Hungary in December 1917.

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