Welcome to the deep dive. We are really thrilled
to have you with us today. Yeah, thanks for joining
us. We've got a fascinating one today. We really
do, because today we are looking at a piece of
history that reads exactly like a Hollywood espionage
thriller. But every single detail actually happened.
Exactly. Today's mission is exploring a single
Wikipedia article concerning one of those, well,
consequential documents of the 20th century.
The Zimmerman Telegram, a massively important
piece of paper. Truly. We are going to uncover
how a single intercepted 160 word coded message
in 1917 just completely altered the course of
global history and, you know, pulled the United
States directly into World War One. Right. And
for you listening, the source material we're
working from today is absolutely packed with
real world spycraft, cryptographic triumphs and
some truly staggering. diplomatic blunders. To
put it mildly. OK, let's unpack this. Set the
scene for us. What exactly is the context surrounding
this infamous telegram? And why was the world
on such a knife edge in early 1917? Well, to
understand the sheer gravity of this telegram,
you really have to put yourself in January 1917.
We are deep into the grinding, brutal stalemate
of World War One. The trench warfare era. Right.
The trenches in Europe have barely moved. Millions
have died. And the German empire is feeling the
squeeze of this massive British naval blockade.
So they're getting desperate. Very desperate.
So the German high demand prepares to make a
massive, deeply risky strategic move. They plan
to resume unrestricted submarine warfare on February
1st. Which essentially means taking the gloves
completely off in the Atlantic Ocean, right?
Precisely. Unrestricted submarine warfare means
German U -boats will sink any ship they encounter
in the Atlantic War Zone. Any ship at all? Any
ship. including neutral passenger and merchant
vessels. I mean, if it has a propeller and it's
heading toward Britain, they're going to torpedo
it. Even if it's flying the American flag. Even
then, the German leadership believes this ruthless
total war tactic is the only way to starve Britain
of supplies. To force them to the negotiating
table. Yeah, within a few months, hopefully.
But there is a massive catch to this plan. They
know the US is going to hate it. Right. They
know that blowing up American civilian and merchant
ships will almost certainly force the neutral
United States. Which has this massive industrial
base. Exactly. To declare war on Germany. So
they are deliberately preparing to poke the bear.
Yes. But they needed a contingency plan for when
the U .S. inevitably got angry and mobilized.
So how does Arthur Zimmerman fit into this desperate
situation? This is where Arthur Zimmerman, the
state secretary in the German Foreign Office,
makes an incredibly audacious move. OK. On January
17th, he dispatches a highly secret, heavily
coded telegram to Heinrich von Eckert, who was
the German ambassador stationed in Mexico at
the time. Right. And the pitch he makes to the
Mexican government in this message is just breathtaking
in its scope. It really is. Zimmerman proposes
that if the United States appears certain to
abandon its neutrality and enter the war, Ambassador
Eckert should approach the Mexican government
with a proposal for a formal military alliance.
And he isn't just asking for moral support either.
Not at all. Zimmerman is offering generous financial
support for Mexico to actively make war against
the United States. And the prize for Mexico is
huge. Yeah. Germany says that after the war is
won, Mexico will get to reconquer its lost territories.
He specifically lists Texas, New Mexico and Arizona.
It's wild. And the telegram even goes a step
further. It instructs the Mexican president to
invite Japan to instantly join this alliance,
asking Mexico to mediate between Germany and
Japan to bring them into the fold against America.
If we connect this to the bigger picture, Germany's
motivations here are quite calculated, even if
the execution was deeply flawed. How so? Well,
Germany had long sought to incite a conflict
between Mexico and the United States. Right.
Why? Because a hot war on the North American
continent would tie down the American military.
That makes sense. If the U .S. Army is fighting
a massive border war in the Southwest, they physically
cannot export arms, munitions, and eventually
troops across the Atlantic to help the European
allies. It's a massive distraction technique.
Just keep America busy in its own backyard. Exactly.
And the Zimmerman Telegram wasn't an isolated,
out of the blue idea. The source material highlights
several previous German provocations aimed at
keeping the U .S. distracted. Right. There were
prior attempts. Yes. For example, there was the
1914 Ipiranga incident where German ships aided
in arming Mexican factions. I remember reading
about that. Then, in 1915, a German naval intelligence
officer named Franz von Rintelen actually handed
Victoriano Huerta $12 million to try and incite
a border war. $12 million back then was a fortune.
A massive sum. And beyond Mexico, there were
even German saboteurs actively operating inside
North America. Oh, like the explosions. Right.
An agent named Lothar Vitske, who was based in
Mexico City, later claimed responsibility for
the massive March 1917 munitions explosion at
the Mare Island Naval Shipyard in California.
He was also heavily suspected in the infamous
Black Tom explosion in New Jersey in 1916. Which
destroyed millions of pounds of American ammunition
destined for Europe. Right. So Germany was actively,
aggressively trying to light a fire in America's
backyard. And from the German perspective, tensions
were already incredibly high on the U .S.-Mexico
border. Very high. General John J. Pershing had
just spent the better part of 1916 leading U
.S. troops into Mexico to try and capture Pancho
Villa. And completely failed. Exactly. So the
Germans are watching this and thinking, well,
Mexico might actually go for this. It wasn't
a totally crazy thought to them. But the logistics
of how this telegram actually gets from Berlin
to the German embassy in Mexico is just a massive
irony. How did they physically send it? The transmission
method is perhaps the most glaring strategic
error in this entire saga. It's unbelievable.
At the very outbreak of the war in 1914, Britain
did something incredibly smart. They dredged
up and physically cut Germany's international
telegraph cables. A direct secure transmission
from Berlin to the rest of the world was virtually
impossible. Right. Germany had to get creative.
One route was sending the message as a radio
transmission through a plant in West Saveville,
New York, which was ironically being monitored
and operated by the U .S. Navy at the time. Exactly.
Another route involved hiding the message inside
a Swedish diplomatic pouch that went from Stockholm
to Buenos Aires and then up to Mexico. But those
routes were unreliable. The most incredible route,
the main one they used, relied on the United
States itself. Yes. Because their own cables
were severed, the German Foreign Office appealed
to the United States State Department. They literally
asked if they could use the American diplomatic
telegraphic system to send messages to their
embassy in Washington. And President Woodrow
Wilson actually agreed to this. He did. He believed
that cooperating with Germany and keeping the
lines of communication open would sustain good
relations. And help facilitate his ultimate goal,
which was brokering a negotiated end to the war.
Right. So the workflow is absurd. The Germans
would hand their messages to the American embassy
in Berlin. OK. Those would be relayed to Copenhagen
and Denmark, forwarded to London, and then sent
across the transatlantic cable to the US by American
telegraph operators. And Germany assumed this
American diplomatic route was completely secure.
They felt very safe using it. But my understanding
is that the US had placed a very strict condition
on this courtesy. All messages sent through the
American system had to be in clear text. Yes.
For anyone unfamiliar, clear text just means
plain unencrypted language. The Americans demanded
to know exactly what the Germans were sending
so they wouldn't be accused of aiding the German
war effort. Exactly. If Zimmerman had sent his
plan to carve up Texas in clear text, the American
telegraph operators would have read it immediately
and massive alarm bills would have gone off.
That was the rule. But Wilson, in his desperate
attempt to be accommodating and foster peace
talks, had recently relaxed those rules. He allowed
the Germans to send coded messages, assuming
they were sensitive peace proposals. So they
took full advantage of that big time. The Germans
actually persuaded the U .S. ambassador in Berlin,
James W. Girard, to accept Zimmerman's explosive
note in its fully coded form. So on January 16th,
1917, the United States State Department essentially
transmitted the very weapon meant to be used
to dismantle their own country. The Americans
literally paid for the telegraph transmission
of their own planned invasion. Yes, they did.
But this relies on the assumption that no one
is listening in on the American diplomatic lines.
And that brings us to the British. Every single
piece of diplomatic traffic passing through the
transatlantic cables which landed in Britain
was being quietly monitored by British intelligence.
Right. Specifically, a highly secretive department
at the Admiralty known as Room 40. Rune 40 was
essentially the World War I equivalent of Bletchley
Park. Exactly. It was filled with brilliant codebreakers,
linguists, and analysts whose sole job was to
intercept and decrypt enemy communications. And
they caught it. They intercepted the Zimmerman
transmission as it bounced through London. Inside
Room 40, an analyst named Nigel DeGray recognized
the code being used. And he had partially decoded
the telegram by the very next day. Here's where
it gets really interesting. How did they get
the specific insight to crack this top -tier
German diplomatic code? It wasn't just raw mathematics.
Not at all. It involved a massive stroke of luck
in a completely different theater of the war.
It's a phenomenal story of global espionage.
Room 40 was dealing with the German diplomatic
code 13040. Okay, 13040. Right. To understand
this, you have to know how codebooks work. They
are essentially massive translation dictionaries.
A specific string of numbers corresponds to a
specific word or phrase. Precisely. Without the
physical book, the numbers are just gibberish.
You might decipher a few common words through
frequency analysis, but a complex diplomatic
message is nearly impossible to read. quickly
without the key. And the British had been slowly
reconstructing code 13040 for years, but they
had massive gaps. Yes. And the missing pieces
to that puzzle were found in the Middle East.
Specifically through a German agent named Wilhelm
Wasmus, he was involved in the Niedermeier Hentig
expedition. Which was a failed German mission
in Afghanistan to try and incite local populations
against British India. Right. The mission fell
apart and Wasmus had to flee for his life. In
his desperate escape, he abandoned his luggage.
Just left it behind. British and allied forces
recovered his baggage and inside they found his
heavily guarded 13040 codebook. Wow. Finding
Wasmus's abandoned codebook provided the crucial
missing keys that allowed the British codebreakers
in London to finally piece together the terrifying
full text of the Zimmerman telegram. So William
Reginald Hall. The chief of Room 40 now holds
the fully decrypted telegram in his hands. Yes,
he does. He is staring at a document that proves
Germany is trying to ally with Mexico and Japan
to carve up the United States. A completely staggering
piece of intelligence. He knows this piece of
paper could completely sway American public opinion
and their neutrality and bring millions of American
troops into the war to save Britain. But he can't
just hand it to Washington. Right. What's fascinating
here is the absolute strategic dilemma this created
for Admiral Hall. It was a monumental intelligence
tightrope. If he just walks up to the American
ambassador and says, look what the Germans are
planning, the Americans are going to immediately
ask, how did you get this? Because to explain
how they got it, Paul would have to admit to
two disastrous things. Exactly. First, the Germans
would instantly read the news, realize their
top -secret 13040 code was completely compromised,
and change all their communication methods overnight,
blinding British intelligence. Right. And second,
the United States would realize that their supposed
ally, Britain, was actively tapping and eavesdropping
on private American diplomatic cables. Paul could
have won the battle but lost the entire intelligence
war. So he actually waited. For three agonizing
weeks while British ships were being sunk by
U -boats, Hall sat on the telegram. That must
have been excruciating. During this time, Nigel
de Grey and another brilliant cryptographer,
William Montgomery, completely finished decrypting
and refining the translation. And then? Finally,
Hall passed it to the British Foreign Office
on February 5th, but strictly warned them not
to release it yet. They needed to engineer a
watertight cover story. They had to explain to
the Americans how they got the coded text and
how they got the plain English translation. Without
ever exposing Room 40's existence or the fact
that they were spying on U .S. cables. And the
cover story they came up with is a master class
in espionage. It really is. The British reasoned
that because the message was relayed from Washington
down to the German embassy in Mexico City, the
commercial telegraph office in Mexico City would
legally have a copy of the coded text on file.
Right, a physical record of the transaction.
So they deploy a British agent in Mexico. He's
known in the files only as Mr. H. Though Sir
Thomas Haller, the British ambassador in Mexico,
later claimed in his autobiography that he was
the operative, Mr. H walks into the commercial
telegraph company in Mexico City, slips an employee
a hefty bribe, and walks out with a physical
copy of the coded telegram. That specific action
was the masterstroke that saved the entire operation.
It provided a brilliant half -truth. A half -truth?
Yes. When the British finally presented the evidence
to the Americans, they could truthfully look
them in the eye and say we bought a copy of this
telegram in Mexico. This perfectly obscured the
fact that they had originally intercepted it
by tapping American lines in London. Furthermore,
when the German embassy in Washington retransmitted
the message down to Mexico City, they didn't
use the newest codes. They encoded it using the
older 1 -3 -Z -40 code because the embassy in
Mexico didn't have the newest code books yet.
Which is the exact code book the British had
just perfected thanks to the luggage left in
Afghanistan. Exactly. So the British hand, the
Americans, the coded text from Mexico, the English
translation, and the third 3 -D -40 code book.
They tell the Americans, don't take our word
for it, verify it yourself. And the Americans
do. They go to their own commercial telegraph
records, pull the exact same coded message they
had transmitted for the Germans weeks prior,
apply the British code book, and read the threat
with their own eyes. It was undeniable proof.
And meanwhile, how did Germany react when they
found out Britain had the message? Because Britain
publicly claimed they stole a physical hard copy
in Mexico, the German Foreign Office completely
refused to believe their cryptographic codes
were compromised. They trusted their math too
much. Way too much. Instead, they idiotically
launched a massive paranoid witch hunt inside
their own embassy in Mexico City. Accusing their
own loyal staff of treason. and leaking the document.
Yes, they never changed their codes, allowing
Room 40 to keep reading their mail for the rest
of the war. It's an astonishing self -own by
the German high command. Yeah. But while the
Germans are chasing ghosts in their embassy,
we have to look at what was actually happening
with the Mexican government. That's a crucial
part of the story. When Ambassador Eckhart finally
presented this audacious proposal to Mexico,
did they ever seriously consider it? The answer
is yes. They took it seriously enough to evaluate
it. When Mexican President Venustiano Carranza
didn't just dismiss it out of hand, he assigned
a formal military commission made up of his top
generals to assess the actual feasibility of
forming an alliance with the German Empire and
launching a military campaign to take over Texas,
New Mexico, and Arizona. Which sounds terrifying
on paper, but when the Mexican generals actually
sit down and apply some cold, hard critical thinking
to this grand German plan, it falls apart instantly.
Precisely. The military commission laid out several
highly logical, deeply practical reasons for
rejecting the alliance. What was the first reason?
First, you have to look at Mexico's domestic
situation. They were in the middle of a brutal,
protracted civil war. Figures like Pancho Villa
and Emiliano Zapata were still actively leading
armed factions. So they weren't unified? Not
at all. President Carranza's own position was
incredibly insecure. He was barely holding the
country together and, in fact, was eventually
assassinated in 1920. Wow. Picking a massive
fight with the United States would have instantly
prompted Washington to heavily arm and support
one of Carranza's domestic rivals, guaranteeing
his downfall. Then there was the reality of the
military hardware. Exactly. The disparity in
military strength was vast. Even if Mexico had
been perfectly united, there is no scenario where
they could successfully invade and hold U .S.
territory. Right. Much of Mexico's military hardware
in 1917 was outdated. Some of it was only a slight
upgrade from the muskets and cannons they used
in the Mexican -American War 70 years prior.
They simply did not have the industrial capacity
to fight a modern war against the U .S. military.
No. But wait, didn't Germany promise generous
financial support? Couldn't Mexico just buy better
weapons? The generals realized that German promise
was entirely empty. The German government had
already told Carranza back in June 1916 that
they couldn't even provide enough gold to help
Mexico stock an independent national bank. The
British naval blockade was starving Germany.
There was no way German ships could deliver mountains
of gold or weapons to Mexican ports. The generals
knew Germany was writing checks it couldn't cash.
Exactly. And even if Mexico somehow found the
money, they would have had to buy those modern
weapons from the ABC nations. The ABC nations
being Argentina, Brazil and Chile. Right. And
this brings up a crucial diplomatic angle. The
ABC nations had actually stepped in to organize
the Niagara Falls Peace Conference in 1914. They
did this specifically to prevent a full -scale
war between the US and Mexico after the US military
occupied the port of Veracruz. So if Mexico suddenly
turned around and launched an unprovoked German
-funded invasion of the U .S. It would completely
betray the ABC nations and ruin relations with
the most powerful countries in South America.
And finally, the generals pointed out the sheer
terrifying logistical impossibility of what Germany
was asking. They were supposed to occupy Texas,
New Mexico and Arizona. That meant trying to
pacify millions of heavily armed English speaking
Americans who were fiercely independent and used
to self -government. It was a complete fantasy.
So Mexico gives a very firm, quiet no. And the
direct result of this logical assessment is that
the U .S. rewards Mexico's neutrality. Right.
On August 31st, 1917, the U .S. officially recognized
the Carranza government as the legitimate permanent
rulers of the country, what diplomats called
de jure recognition. They did this specifically
to stabilize Carranza and ensure that Mexico
remains strictly out of World War One. Yes. But
let's rewind a few months to the moment the American
public actually finds out about this plot. President
Wilson receives the authenticated telegram from
the British in late February. He does. The source
notes he feels much indignation, which is a very
polite diplomatic way of saying he was furious.
He releases it to the Associated Press on March
1st, 1917. And the public reaction is explosive.
But it's not universally supportive of war right
away. No. It's important to understand how complex
and divided American public opinion was at that
exact moment. Right. On one hand, many Americans
already held strong anti -Mexican and anti -German
views. And tensions on the southern border were
at a boiling point because of the raids by Pancho
Villa. But on the other hand, there were massive.
deeply entrenched anti -war sentiments across
the country. President Wilson had literally just
won re -election a few months prior on the slogan,
He Kept Us Out of War. Right. And you have heavily
influential media outlets, most notably the Hearst
Press Empire, and various groups of German Americans
and Irish Americans who were deeply skeptical
of British intentions. Very skeptical. When they
read this telegram in the newspapers, they looked
at the convenient cover story that the document
was just found in Mexico and they assumed it
was fake. They loudly argued that the entire
telegram was an elaborate forgery. A piece of
black propaganda created by British intelligence
to trick the United States into shedding American
blood to save the British Empire. And the Wilson
administration is stuck in a terrible position.
They have the confidential proof from the British,
the code books, and the commercial telegraph
receipts. But they can't make that hard evidence
public without completely blowing Room 40's cover
and ruining British intelligence. The Fortree
theories are gaining serious traction. The anti
-war movement is seizing on this doubt. The U
.S. government needs a miracle to prove the document
is real without revealing their sources. And
they get that miracle from the most baffling,
unlikely source imaginable. Arthur Zimmerman
himself. Yes. It is truly one of the most catastrophic
public relations blunders in all of diplomatic
history. It's hard to believe it actually happened.
On March 3, just two days after the telegram
hits the front pages, while the forgery theories
are working perfectly in Germany's favor, Zimmerman
holds a press conference in Berlin. An American
journalist asks him point blank about the telegram.
And instead of denying it, instead of calling
it a British lie, Zimmerman simply says, I cannot
deny it. It is true. It's astonishing. He didn't
just slip up once either. On March 29th, he gave
a formal speech in the Reichstag, the German
parliament, and again fully admitted the telegram
was genuine. Why did he do this? He was facing
intense criticism from political rivals inside
Germany who thought he wasn't doing enough to
prepare for America entering the war. So he admitted
to the telegram to prove to his domestic critics
that he was actively trying to build alliances.
Exactly. He tried to justify it by saying it
was only a contingency plan, but the geopolitical
damage was entirely done. By defending his own
ego, he personally squashed the American forgery
theories and handed the allies a blank check.
He really did. So what does this all mean? You
have this terrifying telegram, publicly authenticated
by the man who wrote it, proposing to carve up
the American Southwest. And at the exact same
time February 1st has passed, Germany's unrestricted
submarine warfare has officially begun. The abstract
threat has become a bloody reality. Exactly.
German U -boats are now actively torpedoing and
sinking American merchant ships in the Atlantic.
American sailors are drowning. President Wilson
had previously tried to arm merchant ships for
self -defense, but anti -war senators had filibustered
and blocked the measure. Now the context has
violently shifted. You have the immediate physical
threat to American lives on the high seas combined
with the existential geopolitical threat outlined
in the Zimmerman telegram. Neutrality is no longer
a defensible position in the eyes of the public
or the government. The demands for action become
completely overwhelming. And on April 6, 1917,
the United States Congress officially votes to
declare their war on the German Empire. With
President Wilson calling for a war to make the
world safe for democracy. The telegram, combined
with the submarines, was the tipping point. And
as a brief, almost comical postscript to the
Grand Alliance proposal, the Japanese government,
who were already fighting on the allied side
and honoring their treaties with Britain, eventually
released a public statement confirming they had
absolutely zero interest in Germany's absurd
offer to switch sides and attack America. The
Zimmermann Telegram completely backfired on every
single conceivable level. It failed to secure
an alliance. It failed to distract the U .S.
Army. It exposed their supposedly unbreakable
codes. And it directly accelerated the entry
of the United States into the war, which ultimately
sealed Germany's defeat. It's an astonishing
sequence of historical dominoes. And there's
a final amazing detail to wrap this up. For decades,
historians assumed that the original typed decryption
of the telegram, the actual physical piece of
paper that Admiral Hall handed to the American
ambassador in London, was lost forever. Likely
tossed in an incinerator along with thousands
of other secret documents from the era. But...
In October 2005, an anonymous historian researching
the UK's government communications headquarters
finally found it. They discovered the original
typescript handed to U .S. Ambassador Walter
Hines Page. And right at the top of the document
scribbled in Admiral William Reginald Hall's
own handwriting are the words, This is the one
handed to Dr. Page and exposed by the president.
It is a remarkable artifact to survive a century
of history, and it connects this entire narrative
directly back to you listening right now. How
so? Well, the Zimmerman Telegram is so much more
than a date you memorize for a history test.
It is a profound real world case study in the
critical importance of information security.
Absolutely. The German High Command arrogantly
assumed their communications were safe. They
actually used American diplomatic cables to transmit
a plan to attack America, which is perhaps the
most spectacular example of unintended consequences
in modern warfare. Furthermore, this entire saga
highlights the immense life -saving value of
critical thinking. We see this perfectly demonstrated
by the Mexican Military Commission, who looked
past the grand promises of reclaimed glory and
objectively analyzed the cold, hard, logistical
realities of the proposal. It really is the ultimate
cautionary tale of acting on arrogant assumptions.
The Germans assumed their 3040 code was mathematically
unbreakable. They assumed Mexico would be blinded
by the temptation of reclaiming Texas. And they
assumed the United States wouldn't find out about
plot until it was too late. And every single
one of those assumptions was dead wrong. Dead
wrong. This raises an important question though
about what we still might not know regarding
this event. Right. History is rarely a perfectly
closed book even a hundred years later. Exactly.
As recently as 2024 it was reported that there
are still six open files regarding the Zimmerman
telegram held securely by the National Archives
at Q in the United Kingdom that have not yet
been declassified. That's fascinating. Well over
a century has passed since this single 160 word
message fundamentally changed the trajectory
of the modern world. Yet as we examine the available
evidence we are left to ponder. What secrets
about the century -old telegram, about the spies
who intercepted it, or the methods they used
are still deemed too dangerous, too sensitive,
or too revealing to share with the world today?