1917
Americans learn of the Zimmerman Telegram
In early 1917 the battle line on the Western Front was in stalemate and Germany was in need of a breakthrough. Moreover the maritime supply routes from North America that kept Britain fed and armed had to be cut — and this meant resorting to unrestricted submarine warfare which would target any ship, neutral or belligerent, carrying explosives or carrying tourists, which ventured into zone around the British Isles. The German High Command believed that the beginning of indiscriminate submarine attacks might bring the United States into the war on the side of the Allies — their shipping was certain to be targeted — and they sought for a way to keep Americans from committing themselves fully to a European war.
The answer seemed to be to encourage a border war between the USA and Mexico which would pin down much of the American army. To that end the German Foreign Minister Artur Zimmerman sent a telegram in January 1917 to the German ambassador that he was to convey to the Mexican government with the following proposition:
We intend to begin on the first of February unrestricted submarine warfare. We shall endeavor in spite of this to keep the United States of America neutral. In the event of this not succeeding, we make Mexico a proposal of alliance on the following basis: make war together, make peace together, generous financial support and an understanding on our part that Mexico is to reconquer the lost territory in Texas, New Mexico, and Arizona. The settlement in detail is left to you. You will inform the President of the above most secretly as soon as the outbreak of war with the United States of America is certain and add the suggestion that he should, on his own initiative, invite Japan to immediate adherence and at the same time mediate between Japan and ourselves. Please call the President’s attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England in a few months to make peace.” Signed, ZIMMERMANN
The problem was that British intelligence agents had decoded the message and wanted to alert the Americans to this act of treachery which would certainly encourage Washington to join the Allies. However, they didn’t want the Germans to know that they had broken their codes or to let the Americans know that they had been tapping into their telegraph cables so it took some time to concoct a cover story that would allow the British government to safely release the contents to the Americans. This they did on February 24 and the expected diplomatic scandal erupted, helping the government of Woodrow Wilson, who a short time before had campaigned on the slogan “He kept us out of war”, to join the campaign against the German Empire.