A Secret German Plot: The Zimmerman Telegram

A secret message, a bold promise, and a fateful mistake—when Germany reached out to Mexico with a shocking proposal, they never expected British spies to be listening. As the telegram’s explosive contents made headlines, outrage swept across America. What happened next would change the course of World War I forever. In this episode, we talk about the famous “Zimmerman Telegram” then we play the quiz game with Comedian Joel Savage!

World War I saw some interesting alliances. It was strange that The Ottoman Empire allied itself with Germany, but they both had enemies in Britain and Russia. Japan had always been a very isolationist country, but became allies with Britain. Italy was allied with Britain despite the fact that they had begun the war allied with the other side. But one of the strangest alliances is one that was attempted by Germany but failed: a German alliance with Mexico. 

So first, let’s meet Arthur Zimmerman. He was a German diplomat who rose through the ranks of the German Foreign Office, until he became Foreign Minister in 1916, overseeing most of Germany’s diplomatic strategies. He was often described as incredibly skilled, but overconfident. Upon assuming the role of Foreign Minister, one of the most important decisions he made was regarding the use of unrestricted submarine warfare. 

At the beginning of the war in 1914, Germany had 30 submarines, known as U-boats which is a shortened version of the delightfully named cognate, Unterseeboote. And during this time the Royal British Navy controlled the seas, which essentially forced a blockade on Germany. They couldn’t get any supplies by sea, and to fight this, these U-boats started attacking Royal Navy and neutral merchant ships. They practiced what was called unrestricted submarine warfare, attacking ships with no warning, a huge departure from the standard prize rules of war.

The other thing that was going on right now was that Britain and France wanted the U.S. to enter the war. At this point, the U.S. hadn’t involved itself in the war other than U.S. Banks helping to prop up Britain and France. Those banks had an interest in the war because if Germany won, they wouldn’t get their billions of dollars back. The U.S. traded heavily with these allied nations, so there was a very strong interest in their side of the war winning. 

Germany knew that the U.S. entering the war was something they didn’t want. At various points during the war, this was expressed by various German officials. The German Emperor, Kaiser Wilhelm III, said “I would rather accept a disadvantageous peace today than to see the United States enter the war.” The German Ambassador to the U.S., Count Johann von Bernstorff, said “Once America is our enemy, it will never be our friend again.” Germany knew that U.S. intervention would be disastrous, but its leaders gambled that they could win the war quickly before the U.S. entered the war. Their underestimation of American power was one of their greatest strategic mistakes.

On May 7, 1915, something happened that sped up the U.S. entry into the war. A German U-Boat, U-20, sank a British passenger ship, The Lusitania,killing almost 1,200 people, including 128 Americans. Immediately, American citizens started calling for the U.S. to retaliate. Public opinion against Germany was rising in the U.S. and as a result, Germany announced they would suspend unrestricted submarine warfare in order to avoid the United States sending men overseas. This was September of 1915.

But they continued attacking ships, including the British ship Sussex, which injured more Americans. This happened in 1916 and after that, they said “Okay, fine we’re going to keep attacking people with our U-boats, but we’ll warn them first.”

But behind the scenes, something else was going on. Once they had appeased the U.S., Arthur Zimmerman was planning to quietly resume unrestricted submarine warfare in February of 1917. And he had a plan to mitigate the risk of the U.S. entering the war. In a risky move, Zimmerman wrote a telegram to a nation he wanted to become a new ally with Germany: Mexico. 

Here’s the full text of the telegram, which was sent on January 16 of 1917. 

“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 Mexico of the above most secretly as soon as the outbreak of war with the United States is certain and suggest that he should, on his own initiative, communicate with Japan suggesting adherence at once to this plan; at the same time, offer to mediate between Germany and Japan.

Please call the President’s attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England to make peace within a few months.”

This message was sent to the German Ambassador in Mexico, Heinrich von Eckardt.

Arthur Zimmerman’s telegram to Mexico was received in January of 1917 and read by not only Germany’s ambassador to Mexico, but it was sent up the chain to Mexico’s President, Venustiano Carranza. He ordered an analysis of the proposal. So it’s important to know what kind of situation Mexico was in in 1917. 

As this telegram was being sent, the Mexican Revolution was coming to an end. It had been going on for 7 years and saw a power struggle between Venustiano, Pancho Villa, Emiliano Zapata, and Álvaro Obregón. It had been a brutal civil war and as a result, the military, and the country, was fractured. The Mexican army was tiny, ill-equipped and poorly trained – mostly because there hadn’t been any sort of unified command structure since 1910. Mostly what was happening at the time was guerrilla warfare carried out by small factions and militias. They had no air force, no tanks and most of their guns were from the 1800s. The government was still working on recovering from the civil war and consolidating power. They had no industrial resources to support any sort of war effort. So even if they wanted to take Germany up on this offer, they couldn’t. Sure – they would have loved to regain the territories of Texas, New Mexico and Arizona, but they simply couldn’t. The most they had the capability of doing were maybe small raids like the one Pancho Villa had led into New Mexico the previous year. Even if they decided to take Germany up on its offer, there’s no way Germany could have even held up their end of the deal. There was still a British naval blockade. Germany couldn’t have gotten troops and supplies to Mexico. Mexico couldn’t risk total war with their closest neighbor. They’d be obliterated and they knew it. So rather than antagonize the U.S., Carranza’s government informed the U.S. that they had no interest in Germany’s plan. Mexico remained neutral in World War I, avoiding conflict with both the U.S. and Germany.

But what is really interesting about this story is how foolish the telegram was. Both in concept and in execution. For Zimmerman, this was a contingency plan in case the U.S. entered the war. But what he didn’t count on was that the very knowledge of this plan was enough to get the U.S. to do exactly that. 

British Intelligence Cryptography Office, known as “Room 40”  intercepted the Zimmerman Telegram almost as quickly as it was sent. It had been encrypted using Germany’s diplomatic cipher 0075, which was a code that the British had already partially cracked. But a British Cryptographer, William Reginald Hall, nicknamed “Blinker,” worked hard to decode this new message and by January 25, 1917 – just 9 days after it was sent – he decoded it, which in turn helped to complete their understanding of Germany’s code. But how did they get the message in the first place?

This is the most baffling part. The war had resulted in Germany’s direct telegram cables being severed to the Western Hemisphere. In order to send anything across the ocean, they relied on neutral diplomatic cables. Those cables belonged to the U.S. So in a way, the U.S. was unknowingly helping Germany by allowing them to send encrypted messages to their embassies in the Americas. In the case of the Zimmerman Telegram, it had traveled from Berlin to Washington, then on to Mexico City via commercial telegraph. On top of that, they sent the thing three different ways simultaneously to make sure it arrived in Mexico City. Zimmerman also sent the message through a Swedish diplomatic telegram service and through radio transmissions. 

The British had already tapped the transatlantic diplomatic cables. Every single message Germany was sending was being intercepted. It was simply a matter of decoding. They received the message from the cables and from intercepting the radio transmission. The problem now was how do they let the United States of America know without letting on that they were intercepting and decoding Germany’s communications. 

Here’s what they did. First off, they sat on it. They didn’t let on that they had the message. They probably realized that the threat of Mexico joining the war was slim, so they was no need to hurry. Secondly, they pretended they stole a hard copy of the telegram in Mexico before relaying it to the U.S.

February came and the unrestricted submarine warfare by German U-boats resumed.  By March, the telegram was being seen by not just American diplomats and leaders, but by the entire world as it was being published in American Newspapers. Americans were incensed that Germany was trying to incite war between Mexico and the U.S. 

Here’s an excerpt from a March 1st newspaper article in the Daily Review, Decatur, IL. “Washington, March 1.- Full official confirmation of Germany’s intrigue to ally Mexico and Japan with her to make war on the United States as revealed last night by the Associated Press, was given today at the White House, the State Department and in the Senate. On the floor of the Senate it was announced that Democratic senators had been authorized to state that the revelations including the text of the instructions from German Foreign Minister Zinmermann to German Minister von Eckhardt, Mexico City, were correct.”

While many Americans were angry, others didn’t believe it. They thought it was a false flag to get the U.S. to join the war effort. Germany didn’t confirm or deny the veracity of the telegram, but some German officials publicly implied it was a forgery. That is, until 2 days later, when on March 3, Arthur Zimmerman admitted it. He said “I cannot deny it. It is true.” In a speech a few weeks later, he said “”I instructed our ambassador in Mexico to propose an alliance with Mexico, should war with the United States break out. I make no secret of it.”

But this was one of the biggest backfires in military history. Remember – Germany wanted to avoid the U.S. going to war. But the anger from the telegram caused the opposite. Even Americans who had previously wanted the U.S. to remain neutral could no longer defend their position. 

U.S. Secretary of State Robert Lansing said, “Germany seeks to destroy the territorial integrity of the United States. This is not merely an insult—it is an act of aggression.” U.S. Senator Henry Cabot Lodge said, “Germany is not merely at war with England and France—she is at war with civilization itself, and now she seeks to bring war to our very borders.” And President Woodrow Wilson said, “The thing that astonished me was that (Zimmermann) should have been so stupid as to send a thing of that kind in a way that was almost certain to be intercepted.” In his speech to congress asking for a declaration of war, he then said, “Germany has filled our unsuspecting homes and offices with spies and sought to turn against us the nations of our own hemisphere.”

Between this and Germany’s continuance of unrestricted submarine warfare, the U.S. now felt that entering the war was unavoidable. On April 6, 1917 – they officially declared that they were entering World War 1. 

If you want to see an original copy of Zimmerman’s Telegram, you can see it in the U.S. National Archives in Washington, D.C., who occasionally puts it on display. There are also the original coded versions along with the decoding work in the London’s National Archives. This message became one of the biggest intelligence coups in history, directly contributing to America’s entry into World War I. 

After the fiasco, Arthur Zimmermann faced intense criticism but stayed on as Germany’s Foreign Minister until August 1917, when he resigned amid growing political turmoil. He faded from public life and never held another government position. Unlike many German officials, he was not prosecuted or exiled after World War I. He lived quietly until his death in 1940, largely forgotten, despite his role in one of history’s most infamous diplomatic blunders. The Internet Says it’s True.

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