GeniusThinking Profile picture
Aug 22, 2025 16 tweets 7 min read Read on X
In 1965, Vietnamese engineers pulled off the biggest feat in engineering history:

They built a 250 km underground city that withstands the US's army, B52 planes, and Mark 77 bombs.

But what they created next nearly destroyed physics forever.

Here's the full story: 🧵 Image
The Cu Chi tunnels weren't just holes in the ground.

They were an underground city: hospitals, kitchens, weapons factories, living quarters.

Some sections went 3 stories deep...
The Viet Cong lived here for YEARS...

*Media: Cross-section diagram of multi-level tunnel system* Image
Image
American B-52s dropped 500-pound bombs. Nothing.

Agent Orange killed the jungle above. The tunnels survived.

Frustrated commanders realized: someone had to go down there.

But who would volunteer for certain death?
Enter the Tunnel Rats.

No special forces training. No glory. Just regular soldiers who raised their hands.

Their loadout? A flashlight, a .45 pistol, and pure courage.

Most were small men. Had to be. The tunnels were 3 feet wide... Image
Image
Why did they volunteer?

"Someone had to do it," said Sgt. Ronald Payne. "If not me, then my buddy would have to."

The army didn't order them. These men CHOSE to crawl into hell.

Here's what waited below... Image
Image
The traps were nightmares:

Bamboo spikes dipped in human feces. Scorpions tied to sticks. Trip wires connected to grenades.

One wrong move = death or infection that killed you slowly.

But the darkness was worse... Image
Imagine: You're crawling. Can't turn around. Can't see 2 inches ahead.

Your flashlight? Makes you a target.

That sound? Could be water drops. Could be an enemy breathing.

You have 0.5 seconds to decide: shoot or die.

*Media: POV shot inside actual tunnel showing cramped conditions*Image
Image
The Viet Cong had home advantage.

They knew every turn, every trap. They could navigate in total darkness.

They'd wait at corners with knives. Let Americans crawl past. Then strike from behind.

The Tunnel Rats had to evolve or die... Image
Innovation born from terror:

They tied rope to their ankles - buddies could pull their bodies out.

Brought attack dogs (until VC used pepper).

Developed a "tunnel pistol" - modified .38 that wouldn't deafen them underground.

Survival required genius. Image
Operation Crimp, January 1966: First major tunnel discovery.

4,000 US troops vs 300 VC in tunnels. The VC escaped.

That's when commanders realized: conventional warfare was useless here.

Enter Operation Cedar Falls... Image
Image
Cedar Falls, 1967: The largest ground operation of the war.

30,000 troops. Tanks. Helicopters. Artillery.

The Tunnel Rats went in first. What they found shocked everyone:

18 miles of tunnels. Underground hospitals performing surgery. Weapons that could arm a battalion. Image
Image
The psychological toll was devastating.

Tunnel Rats developed unique PTSD. Couldn't sleep in dark rooms. Jumped at small sounds.

"You aged 10 years in 10 minutes down there," one veteran said.

Many never spoke about it for decades. Image
By war's end, Tunnel Rats had explored over 100 tunnel systems.

Casualty rate? Horrific. But they gathered intel that saved thousands.

No medals. No movies. Just men who crawled through hell.

Their legacy? Proving courage has no size limit. Image
Image
If this story grabbed you, join my mission:

"Schools hide the best history stories. I dig up the wild, forgotten moments that shaped our world."

Follow @GeniusGTX for the genius moments history class never taught you.

Written by @ToanTruongGTX.
Thank you for reading this thread.

What’s your ONE big takeaway from this story?

Follow me @GeniusGTX for more threads about the hidden brilliance of ancient civilizations.

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with GeniusThinking

GeniusThinking Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @GeniusGTX

Jan 25
I'm obsessed with cognitive biases.

A "cognitive bias" is a systematic error in thinking that destroys decision-making.

11 most powerful (and dangerous) cognitive biases I've found: 🧵

1. Survivorship Bias: Image
1. Survivorship Bias:

We focus on the winners and ignore the losers.

We study the college dropout billionaires but ignore the thousands of dropouts who failed.

Success leaves clues, but failure teaches lessons. Image
2. The Sunk Cost Fallacy:

We cling to things just because we’ve already invested time or money in them.

We refuse to quit a bad job or project because we "can't let that effort go to waste."

Don't throw good time after bad. Image
Read 13 tweets
Jan 20
PHILOSOPHICAL RAZORS are a mental rule of thumbs that "shaves off" bad explanations and stupidity in your decision-making.

Here are the 8 sharpest Razors to upgrade your thinking instantly: 🧵 Image
Image
1/ Occam's Razor

The simplest explanation is usually the correct one.

If you hear hoofbeats in Texas, think horses, not zebras.

Don't overcomplicate solutions. Complexity is often just a mask for confusion. Image
2/ Hanlon's Razor

Never attribute to malice that which is adequately explained by stupidity.

The guy cutting you off isn't evil; he's probably just distracted or a bad driver.

This razor saves you from unnecessary anger and paranoia. Image
Read 10 tweets
Jan 19
He was the most powerful man on earth:

Marcus Aurelius.

He wrote "Meditations" to keep himself sane while ruling an empire. He never intended for it to be published.

Here are 8 of his best short ideas from one of the greatest stoics in history: Image
Image
1. The Obstacle is the Way

"The impediment to action advances action. What stands in the way becomes the way."

Stop wishing for things to be easy.
Use the challenge as fuel.

The struggle isn't blocking the path, it *is* the path.
2. On Anxiety

"Today I escaped anxiety. Or no, I discarded it, because it was within me, not outside."

Stress doesn't come from your boss, the market, or the traffic. It comes from your judgment of them.

Change the judgment, remove the stress.
Read 12 tweets
Jan 17
I used to be stressed out of my mind and wasted years making terrible decisions.

Then I spent hours studying Charlie Munger’s letters to learn his mental models on decision-making & problem solving.

Here're are the top 5 I've collected: 🧵 Image
Image
Why do you need Mental Models?

Most people try to solve problems with raw intelligence. It's exhausting.

Munger says: "To a man with a hammer, everything looks like a nail."

You need a toolbox. Models don't tell you what to think, but how to think.

Here're Munger's best 5: Image
1. Inversion

"Tell me where I'm going to die, so I'll never go there."

Don't just look for the secret to success. Figure out exactly what causes failure—and avoid that.

It is far easier to avoid stupidity than it is to achieve genius.
Read 10 tweets
Jan 16
A "Paradox" is a statement that seems contradictory but actually contains a hidden truth.

Once you see them, your worldview changes forever.

Here are my 10 favorite mind-bending paradoxes that will upgrade your thinking & decision making: 🧵

1. The Paradox of Choice Image
1. The Paradox of Choice:

Logic says more options = more freedom. Psychology says more options = anxiety and analysis paralysis.

When you have too many choices, you are less likely to pick one, and less satisfied with the one you do pick.

Constraints create creativity. Image
2. The Stockdale Paradox:

Named after Admiral James Stockdale, a prisoner of war for 7 years.

He survived by doing two contradictory things:

• Maintaining faith that he would prevail in the end.
• Confronting the brutal facts of his current reality.

Blind optimism kills. Image
Read 15 tweets
Jan 15
I'm obsessed with cognitive biases.

A "cognitive bias" is a systematic error in thinking that destroys decision-making.

11 most powerful (and dangerous) cognitive biases I've found: 🧵
1. The Spotlight Effect:

We constantly overestimate how much people notice our appearance or mistakes.

The truth? Everyone is too worried about themselves to worry about you.

You are not the main character in their movie. Image
2. Survivorship Bias:

We focus on the winners and ignore the losers.

We study the college dropout billionaires but ignore the thousands of dropouts who failed.

Success leaves clues, but failure teaches lessons. Image
Read 15 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(