The US entered WWI after the  Zimmermann Telegram was intercepted by the British where Germany asked Mexico to join the War against the US. US entering the War turned the tide in favor of the Allies as battle fatigue started overpowering Germany and Russia. Russia saw the Czar abdicating while Germany saw its sailors refusing to fight. The War ended with Germany signing an armistice agreement with the Allies on November 11, 1918. During the course of the war, women employment reached a peak due to labor shortage as a big chunk of the labor force was fighting on the frontlines.