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. -Zimmermann Telegram, 1917

A. It led President Wilson to issue a proclamation reinforcing U.S. neutrality.

B. It influenced President Wilson to order attacks on German merchant ships.

C. It appealed to Mexicans and caused Mexico to join the war as a German ally.

D. It engaged Americans and generated U.S. popular support for the declaration of war.

We are referring to the Zimmerman telegraph that the government of Germany sent to the Mexican government during World War I, and was intercepted by the United States Army. This action engaged Americans and generated U.S. popular support for the declaration of war. Of course, Mexico did not accept.

The other incident that moved President Woodrow Wilson to enter the war was the sinking of the Lusitania ship by the German navy. The United States officially entered World War 1 on April 6, 1917.