But as the war unfolded in Europe, an intercepted telegram sent by the German Foreign Secretary, Arthur Zimmermann, to the Mexican government inflamed the U.S. public opinion and was one of the ...

British Foreign Affairs Office, London, February, 23rd 1917. In the afternoon, Arthur Balfour, the foreign secretary of the United Kingdom, hands the American Ambassador Walter Page a sheet of paper.

After the Zimmermann telegram incident in early 1917, however, in which Germany promised Mexico U.S. territory in return for helping them in the war, America entered the conflict. "The April 1917 ...