Thomas Boghardt, author of The Zimmermann Telegram: Intelligence, Diplomacy, and America’s Entry into World War One, explained why Germany sent the telegram to Mexico; how it was intercepted by the British; and how its discovery influenced American public opinion. The coded telegram, dispatched by Foreign Secretary Arthur Zimmermann to the German ambassador in Mexico in anticipation of further unrestricted submarine warfare, instructed Ambassador Eckardt that if the U.S. appeared likely to enter the war, he was to approach the Mexican government with a proposal for a military alliance. Mexico was promised territories in Texas, New Mexico, and Arizona. Eckardt was also instructed to urge Mexico to help broker an alliance between Germany and the Japanese Empire. News of the correspondence was made public after British intelligence intercepted the communication.
The National Archives in Washington DC hosted this event.