Weird History

The Biggest Mistakes That Changed History  

Troy Brownfield
12.4k votes 3.7k voters 312.5k views 12 items

List Rules Vote up the most momentous mistakes in world history.

You know when you've made a big mistake. Sure, there have been tests that you thought you aced or dates that you thought went well – but you know when you've made a really big blunder. Now imagine that your miscalculation is so large, it changes the course of history. We're taking a look at some of the worst – and best – historical mistakes, those with effects you can still see today.

Some of these mistakes that changed history were tragic miscalculations; others were fortuitous accidents. Read on for a list of historical events that were a mistake and their surprising consequences.

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Alexander Fleming Forgot To Clean His Lab
Alexander Fleming Forgot To Cl... is listed (or ranked) 1 on the list The Biggest Mistakes That Changed History
Photo:  Rajitha Ranasinghe/Flickr/CC BY 2.0

Alexander Fleming is credited with discovering penicillin in 1928 – and his methodology stemmed from forgetting to do the dishes.

Fleming spent the month of August on holiday with his family. Upon his return, he noticed that one of his petri dishes of staphylococci had grown a mold that destroyed the sample around it. He then grew the mold in a pure culture and discovered it could annihilate gram-positive pathogens.

Penicillin didn't catch on for several years, but once it did, it was widely used to treat wounded Allies in WWII, saving countless lives.

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D-Day Paratroopers Scattered All Over The Beaches
D-Day Paratroopers Scattered A... is listed (or ranked) 2 on the list The Biggest Mistakes That Changed History
Photo: Sgt. Johnson/Wikimedia Commons/Public Domain

One crucial component of the D-Day invasion was the dropping of the 101st and 82nd Airborne Divisions overnight prior to the amphibious attack on the beaches of France. As the drops began, however, bad weather, anti-aircraft fire, and other factors led to the wide dispersal of Allied paratroopers. While this dispersal did create roadblocks in achieving the invasion's initial objectives, it actually aided the invasion overall. 

The dispersal sufficiently confused the German command structure. American and British forces seemed to be everywhere, attacking a variety of targets, and operating with seemingly no centralized base or command structure. One reason for this was that the teams were formed based on improvisation – soldiers adapted to conditions wherever they landed.

The Germans were unsure if this was the full invasion, a partial invasion, or an extremely elaborate prank. Further, much of the German command was scattered itself – many were training offsite. 

While the scattering of forces complicated matters, it did enable the element of surprise and build upon other deception tactics to keep the German forces in disarray.

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Japan Picked The Wrong Targets In Hawaii
Japan Picked The Wrong Targets... is listed (or ranked) 3 on the list The Biggest Mistakes That Changed History
Photo:  Prayitno/Flickr/CC BY 2.0

Japan's attack on December 7, 1941, concentrated most of its fire on American battleships, a strategy the Japanese believed would hamper US power at sea. As such, Japan's planes didn’t concentrate on the base’s fuel reserves, repair yards, or, incredibly, the aircraft carriers present. Thus, when the smoke cleared, the US kicked their repair yard into full gear and was able to return ships to sea quickly. As the conflict progressed, US naval dominance eventually came from submarines – and aircraft carriers.


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Militaries Invaded Russia During The Winter
Militaries Invaded Russia Duri... is listed (or ranked) 4 on the list The Biggest Mistakes That Changed History
Photo: Unknown/Max Pixel/Public Domain

In 1708, Sweden invaded Russia during a winter so fierce that even Venice’s port froze. The invaders lost 16,000 men in that particular push. Just over 100 years later, Napoleon also attempted an occupation that began in the summer. By late fall, he’d lost thousands of soldiers and, though he succeeded in occupying Moscow, he eventually had to retreat.

The most famous example, however, occurred during WWII. Hitler believed he could take Russia before winter – but his army wasn’t ready when winter finally did come. In fact, things went so poorly in Russia that Hitler lost approximately 750,000 men before November.

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