The Butterfly Effect: 20 Small Mistakes That Brought Down Entire Empires

Although it seemed impregnable in the face of the Ottoman assault in 1453, the city of Constantinople fell because someone had forgotten to lock a side gate known as the Kerkoporta. The Ottoman forces discovered this open gate and rushed inside, quickly defeating the outnumbered defenders from within. Imagine glancing over at your front door and realizing that Europe might still be united under the banner of Christianity if you had just taken the time to check that latch—just that one time.

The driver of Archduke Ferdinand’s car mistakenly took a wrong turn during the assassination attempt, as another attempt had already failed earlier that day. The car he was driving broke down as he was backing up, which allowed Gavrilo Princip to fire his famous shot from the side of the car. In other words, a wrong turn triggered World War I and turned the entire world upside down.

During the Civil War, a Confederate soldier dropped a copy of Special Order No. 191, which detailed General Lee’s entire plan to invade the North. Union troops discovered these documents rolled up around three cigars and immediately turned them over to their military commanders. This stroke of luck enabled the Union to halt the momentum of the Confederate forces during the Battle of Antietam.

When he saw the insurgents approaching during the storming of the Bastille, the governor did not order a counterattack because he could not find the keys to certain gates. This slight delay allowed the revolutionaries to enter the outer courtyard and overwhelm the fortress’s defenses.

A British loyalist slipped a note into the commander’s mailbox to warn him of George Washington’s attack on the Delaware. Distracted, the commander put the message in his pocket without reading it; it was found later, after he surrendered the next day. It’s hard to believe that the United States could have lost the war simply because one guy didn’t take five seconds to read his mail.

Ironically, a steel empire sank into the Atlantic Ocean because someone had misplaced the key to the locker containing the binoculars. The lookouts were forced to spot icebergs with the naked eye in the middle of the night because they couldn’t access their equipment. A simple piece of metal kept the crew safe while the Titanic headed toward disaster.

The Great Wall was unable to prevent invaders from entering China because a general had left the gate wide open. While he was busy building this gigantic structure, the Manchus led their army through the Shanhai Pass after the general refused to defend his post. He did this simply because his wife was cheating on him—that’s all.

History books claim that Napoleon might have turned the tide of battle at Waterloo if his backside hadn’t let him down that day. Some claim that he suffered from particularly painful hemorrhoids that forced him to remain in his command tent when he should have been on the battlefield. One cannot help but sympathize with a man whose physical ailments may have cost him his entire European empire.

Montezuma II panicked when the Spaniards arrived with their advanced technology and decided to let them into his capital. He could have confronted Cortés on the beach, but instead, he offered the foreigners a guided tour of Tenochtitlan. Offering hospitality to your enemy is never a good decision.

Alexander the Great was only 32 years old when he died without naming a successor to his vast empire. He is said to have told his advisors that the empire should go to “the strongest,” which divided his empire into rival factions.

Mission control had to destroy the Mariner 1 spacecraft because it had veered off its launch trajectory. Engineers discovered that someone had forgotten to include a hyphen in the navigation code, which cost taxpayers billions of dollars.

After their great victory that morning against the Texans, the Mexican soldiers took off their boots and socks to go to sleep. They didn’t think anyone would dare to attack in the middle of a sweltering summer day, but General Sam Houston had other ideas. Because of the sleeping soldiers and a lack of coffee, Mexico unwittingly handed Texas over to us.

Agamemnon offended the goddess Artemis by killing a sacred stag, which resulted in a complete lack of wind for his fleet as it sailed toward Troy. This minor act of arrogance forced him to make a horrific personal sacrifice so that his ships could set sail again. The decade of war that followed destroyed Troy and left the Greek kingdoms in a state of utter desolation.

When the Khwarezmian Empire executed a group of Mongol merchants and humiliated Genghis Khan’s ambassadors, its leaders had no idea they were stirring up a hornet’s nest. The Great Khan responded by mobilizing his entire army to wipe that empire off the face of the Earth. You’d be wise to think twice before being rude to a delivery person.

A German pilot accidentally entered Belgian airspace while unfolding a map and was forced to make an emergency landing behind enemy lines. He attempted to destroy the enemy’s plans for the invasion of France, but Belgian forces captured him before he could burn the documents.

Henry VIII decided to throw a tantrum and found Protestantism because the pope had refused to grant him a divorce. This marked the beginning of the English Reformation and forever changed the religious makeup of the Western world. Who could have imagined that a failed relationship could spark a war that would last for hundreds of years?

The history of space exploration was forever changed by a small rubber O-ring that lost its elasticity due to the cold. Engineers had warned about this temperature, but the launch went ahead anyway, leading to a tragedy that brought the space shuttle program to a standstill for years. The failure of this tiny component demonstrated that even the most complex machines are only as strong as their weakest part.

Russia lost its leadership because Nicholas II trusted a mystical madman named Rasputin. His healing powers seemed to be the only thing capable of curing the hemophilia from which the heir to the throne suffered, which provoked the wrath of the Russian elite. A single fanatical healer led to genocide, and world history was never the same again.

Humanity lost centuries of ancestral knowledge when small fires—left unattended by employees of the Library of Alexandria—broke out. Whether they were started by accident or malice, Rome never recovered from the loss of these intellectual treasures.

During the siege of Vienna, a spy managed to slip through the Ottoman lines to deliver a message requesting help from the King of Poland. He did so by disguising himself as a Turk and making use of his knowledge of their customs, particularly their love of coffee. Had he not been such a convincing actor, the city would have fallen, and the history of Europe would be very different today.