The Zimmerman Note is one of the most important documents in U.S. and world history because this letter initiated the participation of the United States in the First World War (WWI). In this letter, Germany invited Mexico to become an ally and start a war against the United States.


The Zimmerman Telegram, or Note, holds great significance for WWI because it gave the U.S. government a reason to declare war against Germany. In 1917, the American government discovered that Foreign Minister Arthur Zimmerman had sent a telegram to the German ambassador in Mexico, in which the former ordered the latter to propose an alliance between Germany and Mexico.

In the note, the minister said that Germany intended to start an unrestricted submarine war to defeat the British. He suggested that Mexico become Germany’s alliy to start a war against the United States and force Japan to switch sides. In return, Mexico would receive financial support to take back the lands lost in the battles of 1840s with the United States, including Texas, New Mexico, California and Arizona. Zimmerman stated, “We shall make war together and together make peace”.

An interesting fact is that the telegram was caught and decrypted not by Americans, but rather by British intelligence. This interception was possible because in 1914, England sent a ship that cut all the cable lines that had allowed Germany to communicate. British intelligence later used the lines that neutral states had provided to Germany, thus intercepting the communication.

Russia was also helpful in decrypting the message that consisted of a digital code. The Russian admiralty handed over to British intelligence a copy of the German naval codebook and a German diplomatic code. For this reason, the British managed to decode and pass the note to the U.S. government.

Germany’s official declaration of unrestricted submarine warfare was made intentionally to draw the United States into conflict. However, Germany hoped that the United States would need more time to respond, as the conflict with Mexico would take the time and forces of the American army. By then, Germany would be in a winning position and would be able to defeat Britain in battle. However, the intercepted telegram made it possible for the United States to avoid manipulation and make the first move. In addition, the statement outraged the U.S. population and caused hatred towards Germany. The United States, which had remained neutral during the previous years of the war, now intended to enter the war.

The Zimmerman Telegram gave the U.S. government facts that pushed them to start a confrontation with the German Empire. President Wilson sought above all to reach a truce and demilitarize Germany. However, the government was forced to enter into a military confrontation to prevent the capture and destruction of its own territories. Consequently, the Zimmerman Letter refers not only to the document itself but also to the reason that the United States entered the First World War.

The intercepted telegram brought about the defeat of the German Empire, since the United States joined the confrontation and ruined the plans for the submarine war. In the end, the German Empire lost the war to the collective efforts of America and Europe.