Zimmermann sent it to the German ambassador in the United States , Johann von Bernstorff . Bernstorff then sent it to the German ambassador in Mexico , Heinrich von Eckardt . The message came as a coded telegram dispatched by the Foreign Secretary of the German Empire , Arthur Zimmermann , on January 16 , 1917 , to the German ambassador in Washington , D.C. , Johann von Bernstorff , at the height of World War I. On January 19 , Bernstorff , per Zimmermann 's request , forwarded the telegram to the German ambassador in Mexico , Heinrich von Eckardt .