If history has taught us anything, it is that we will make mistakes. Big ones, unfortunately. Any history buff knows that there are more stories to tell about huge screw-ups than great successes. Even though — according to Winston Churchill — “history is written by the victors,” there are some historical screw-ups so colossal that decades, centuries, or even millennia later, we can’t quite manage to forget them.

It is almost impossible to pick one historical mistake that is the all-time worst. According to Business Insider, the worst mistake in history when calculated in terms of monetary loss is the meltdown at Chernobyl caused by faulty equipment and a chain of unfortunate events during a test. When adjusted for inflation, it is calculated to have cost a total of $720 billion in damages. While no one disputes the massive impact of this horrible mistake, some of our biggest screw-ups in history happened years before nuclear energy was even a theoretical concept. As the Brainscape staff was reviewing flashcards for our History Buff package, we decided that the following eight screw-ups are among the most colossal in history.

1. Franz Ferdinand’s driver makes the wrong turn that starts World War I

Most historians pinpoint the assassination of Austrian Archduke Ferdinand and his wife as the inciting event for World War I. This event was almost avoided entirely when the driver deflected a bomb away from the car during an earlier assassination attempt that day. Unfortunately, when the duke went to visit the victims of that bomb at the hospital, the driver made a wrong turn that took the car right into the path of one of the original (would-be) assassins, Gavrilo Princip. Princip took advantage of this second chance to shoot the duke and duchess, and the rest is history.

2. An open gate leads to the fall of Constantinople, marking the end of the Roman Empire

When the Ottoman Turks attacked Constantinople in 1453, they originally had little chance of taking the city. While the Byzantines were fewer in number, they had the tactical advantage provided by the highly secure walls surrounding the city. The Byzantines made one huge error, though: they forgot to close one of the gates. The Ottoman armies came into the city through the open gate, raised their flag, and quickly took control of Constantinople.

3. Napoleon, and later Hitler, invade Russia without preparing for winter

When Napoleon Bonaparte led the strongest army ever assembled in continental Europe to take over Russia in June 1812, the campaign was only supposed to take a short amount of time. Unfortunately, Russian armies held out longer than expected and ended up fighting in the bitter cold Russian winter. Most of Napoleon’s army was killed either by the Russians or simply by disease and exposure. The decimated army could not hold out and was later famously defeated for good at Waterloo. Interestingly enough, Hitler made the same miscalculation over a century later when he sent some of his troops to invade Russia without proper winter supplies.

4. The Titanic fails to stock enough lifeboats for the passengers onboard

The Titanic was a technological miracle in the eyes of people at the time and was termed “unsinkable.” As we all now know, the ship did sink after hitting an iceberg on its maiden voyage, dooming many passengers to drown or freeze due to a shortage of lifeboats.

5. The British outsource protection of the British Isles to their invaders

In the early 440s, leaders of the British Isles decided that in order to deal with their many invasions, they would outsource protection of the islands to Anglo-Saxon mercenaries. Unfortunately, when the Anglo-Saxons arrived to “protect” the islands, they quickly realized that the people were defenseless and attempted to take over the British Isles for themselves, resulting in years of violent conflict.

6. Mexico loses the Texas Revolution by getting distracted at the Alamo

Mexican General Antonio López de Santa Anna was marching his troops to meet the Texan revolutionaries in battle when he decided to make a detour at the Alamo to teach a lesson to the rebellious town. Although he won the battle and managed to take the Alamo, the “example” he set there only further angered the rebellion. The added motivation from Santa Anna’s slight to the Texans at the Alamo and the resulting troops lost on the Mexican side ended up costing Mexico the war, allowing Texas to become an independent republic and to eventually join the United States.

7. The Austrian army fights itself, losing 10,000 troops and allowing the Turkish soldiers to take the surrounding countryside

A miscommunication between a group of scouts and infantrymen speaking different languages, massive panic, and quite possibly a large amount of alcohol caused the Austrian army to fight itself at the Battle of Karansebes in 1788. The Austrian army was waiting for enemy Turkish troops to arrive but one night fell into a chaotic battle with itself caused by mass confusion. About two days later the real Turkish army arrived to find the Austrians already badly wounded, allowing them to take over parts of what is now Romania.

8. The Mars Climate Orbiter is lost due to the conflicting uses of both metric and English units of measurement

As part of the Mars Surveyor ’98 program, NASA launched the Mars Climate Orbiter, a robotic space probe, to study the Martian climate in December 1998. Unfortunately, the launch resulted in mission failure in 1999, when the spacecraft disintegrated in Mars’ upper atmosphere. The reason for the failure was a miscommunication between NASA and Lockheed Martin, the manufacturer: one used the metric units of newton-seconds, while the other used pound-seconds. The mission had cost more than $300 million.

Some of these screw-ups can be attributed to miscalculations. Others were caused by pure stupidity or even simple bad luck. Still, every decade we experience a new screw-up that changes history forever. Hopefully though, by learning from some of our historical mistakes, we can avoid repeating them. The more you explore history, the more you will find colossal mistakes. What do you think was our biggest screw-up of all time?