The Significance of the Zimmermann Telegram

Significance Zimmermann Telegram

Many historians consider the United States’ entry into World War I to be a turning point in the war. There were many factors that ultimately brought the US into the war, though the significance of the Zimmermann Telegram cannot be understated.

When World War I broke out in 1914, the United States had a firm commitment to remain neutral. Public opinion in the country was decidedly anti-war and Americans largely viewed the war as a conflict among Europeans.

As the events of the war unfolded, the United States increasingly became at odds with Germany. The German policy of unrestricted submarine warfare led to the inevitable deaths of US citizens across the Atlantic shipping lanes.

The German sinking of the passenger cruise liner RMS Lusitania in 1915 resulted in the death of 128 American citizens. In the aftermath Germany complied with the American demand to end its unrestricted submarine warfare and attacks on non-warships.

Despite the atrocity the United States avoided calls to enter the war and remained neutral. President Woodrow Wilson narrowly won reelection in 1916 after running on the slogan “He Kept Us Out of War,” cementing himself as the candidate seeking peace.

However, German actions in early 1917 would inevitably sway US public opinion far enough to the point that a majority of Americans supported entering the war.

The significance of the Zimmermann Telegram and resumption of German unrestricted submarine warfare played large roles in the eventual declaration of war.

What Was the Zimmermann Telegram?

The Zimmermann Telegram was a note sent from German Foreign Minister Arthur Zimmermann to the German Ambassador to Mexico Heinrich von Eckardt. Zimmermann sent the telegram on January 16, 1917, but given communication delays at the time, von Eckardt did not receive the note until January 19th.

The Zimmermann Telegram proposed an alliance between Germany and Mexico and promised Mexico the lands of their former territories in modern-day Texas, Arizona, and New Mexico in return for attacking the United States. Germany would help to finance said war.

The Germans hoped that if they could sway the Mexicans to join their side, a US-Mexico war could keep the US out of the European conflict. In addition, with America tied down at their southern border there was the potential for reduced shipments of munitions and supplies to the Allies.

Zimmermann knew that the United States was likely to join the war on the Allied side in the near future. Germany had plans to resume their unrestricted submarine warfare on February 1, 1917 in the hopes of sinking so many British supply ships that they could force them to sue for peace.

US Entry into WWI and Zimmermann Telegram Timeline

Such actions would inevitably draw the US into the war as American merchant ships would also be targeted. Hence, from the German standpoint, they had little to lose through the proposed offer to Mexico.

British codebreakers from the infamous “Room 40” intercepted the message just a day after Zimmermann sent it. However, they waited over a month before delivering the decoded message to the United States.

When a shocked President Woodrow Wilson learned of the telegram, he released the details to the media. Headlines on March 1st announced the German plot and led to mass outrage across the US.

The Zimmermann Telegram Transcript

How the British possessed the Zimmermann Telegram put them in an awkward position. At the beginning of the war the British cut the German telegraph cables spanning the Atlantic.

Thus, in order to send messages across the ocean, Germany needed to utilize neutral countries’ transmission lines. The US allowed Germany to utilize their lines, under the guise that not doing so could harm to peace talks.

Thus, the Zimmermann Telegram discussing an alliance against the United States was actually delivered using US telegraph transmission lines.

Zimmermann Telegram coded message
Copy of the coded Zimmermann Telegram via Wikimedia

Accordingly, Britain was spying on nearly all American transmissions throughout the war. Should they make the US aware of this fact by disclosing the contents of the Zimmermann Telegram it would put them in an awkward spot.1

The British were able to discover a workaround, by obtaining a physical copy of the telegram in Mexico showing that version to the US instead and avoiding a potential liability to a future ally.

Below is a transcript of the Zimmermann Telegram.2

“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 or 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.”


The Reactions of Mexico and Japan

While the United States appropriately responded with outrage to the Zimmermann Telegram, other countries responded differently.

At the time of World War I, the Mexican civil war raged. In a multilayered conflict, various forces vied for control of Mexico and the country suffered through years of conflict.

By October 1915 the US officially recognized the legitimacy of the Carranza presidency and the two governments worked together to extinguish the threat of other revolutionaries such as Pancho Villa.

Thus, at the time of the Zimmermann Telegram, Mexico was in little position to declare war upon the United States.

Nevertheless, when the message reached Carranza, he put together a military commission to assess the viability of the proposal. The results of the commission suggested that war with the US would be futile.

Political cartoon displaying Germany, Mexico and Japan carving up the United States via LOC

The commission determined that the Mexican army was simply no match for the US military. Carranza also had a very delicate grip on power. A declaration of war against the United States could dissolve that hold and prop up his opponents.

In addition, Mexico severely doubted that Germany could follow up on its offer to finance the war. Mexico was the direct correspondent and target of Germany’s interests, however, the telegram also explicitly mentioned Japan as well.

At the beginning of the war Japan allied with Britain and France against Germany. Though they played a small role in the war, Germany thought Mexico could potentially align with Japan to attack the US west coast.

The Zimmerman Telegram explicitly omitted California for the Mexicans as they believed the acquisition of California could be enticing for Japan.3

The Significance of the Zimmermann Telegram in WWI

The Zimmermann Telegram had great significance on persuading the United States to join World War I and thus help turn the tide of the war in the allies favor. Public opinion decidedly turned against Germany and the use of unrestricted submarine warfare against American merchant shipping had drastic repercussions.

The audacity of the German conspiracy behind their backs incensed Americans. So much so, in fact, that several leaders suggested that Britain forged the telegram with the intent to draw the US into the war.

This view did not hold when Arthur Zimmermann himself confirmed—on two separate occasions—that he sent the telegram. It was an odd move, but the unapologetic admittance of the plot further swung American public opinion in favor of entering the war.4

The Zimmermann Telegram cannot claim all the credit for American entry into WWI. The resumption of German unrestricted submarine warfare in February led to the sinking of dozens more US merchant ships. Many American lives were lost in the attacks.

Wilson declaration of war World War I
Newspaper reports Wilson’s declaration of war via LOC

The audacity of Germany violating international maritime law and refusing to recognize US freedom of the seas forced America to defend its “honor.” 

Woodrow Wilson called a joint session of Congress on April 2, 1917. Citing the loss of American lives due to unrestricted submarine warfare and the Zimmermann Telegram attempt to “stir up enemies against us at our very doors,” Wilson asked Congress for a declaration of war.

Congress acquiesced to the request and delivered a joint war resolution on April 6, 1917. The United States was officially in the war to the great detriment of their German adversaries. The United States was a relative newcomer to the world stage thanks to the Roosevelt Corollary, but the fresh troops and economic might made a significant difference.

The significance and role of the Zimmermann Telegram in leading to this outcome is one that is debated by historians. Most concur that the telegram played a large role, though it was not as important as the resumption of unrestricted submarine warfare.


To learn more about US history, check out this timeline of the history of the United States.


1) Stibbe, Matthew. Central European History, vol. 47, no. 3, 2014, pp. 663–65. JSTOR,

2) Telegram from United States Ambassador Walter Page to President Woodrow Wilson Conveying a Translation of the Zimmermann Telegram; 2/24/1917; 862.20212 / 57 through 862.20212 / 311; Central Decimal Files, 1910 – 1963; General Records of the Department of State, Record Group 59; National Archives at College Park, College Park, MD.

3) Keylor, William R. The International History Review, vol. 37, no. 2, 2015, pp. 414–16. JSTOR,

4) Yeh, Puong Fei. “The Role of the Zimmermann Telegram in Spurring America’s Entry into the First World War.” American Intelligence Journal, vol. 32, no. 1, 2015, pp. 61–64. JSTOR,

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