The MAIN Causes of WWI

So, what were the causes of WWI?

(Listen to the entire episode here!)

By the early 1900s Europe is solidly in charge of the world, thanks to a few hundred years of challenging authority, innovating, conquering, subjugating, and industrializing. But now they’ve hit a snag because they’re running out of land to conquer – it’s the original “First World Problem.” Also, this whole “balance of power” thing that was created after Napoleon isn’t working so well any more. Some new powers are rising, like Germany, and shaking things up. But also, all of the European countries want to be on top – they don’t really want a balance of power. They’re just saying that so they don’t look like jerks.

Basically, the early 1900s is like that point in Survivor when your alliance easily has the numbers to keep voting off the mGooGoo tribe or whatever. But then you look around and realize that after the other tribe is gone, you’re going to have to start voting each other off. And you don’t want to get blindsided… so maybe you should do the blindsiding… Is that crazy? It seems crazy. The power alliance turns on each other and some rando who had three lines all season ends up winning because all their friends are on the jury. (That’s the U.S., by the way. We’re the rando.)

Anyway. Even though I think that my Survivor analogy is a perfectly comprehensive analysis of the causes of World War I, my producers tell me it’s not. So, in general, there are four main causes of World War I. And it’s adorable because the causes actually spell out the word MAIN. These are the moments that history teachers live for.

(By the way, are you sitting in your car wondering, “Does she really have producers? I mean, the show is pretty good if it’s just her in her kitchen while her baby’s asleep but if this is like a professional thing then I may have to rethink my expectations…” Don’t worry – it’s the first one.)


The first long-term cause of World War I is militarism. As industrialization advanced, so did military technology. The size and strength of the various European militaries grew exponentially, especially in Germany. And this freaked everyone out. Britain had been dominating the world militarily for a few hundred years but here comes Germany pulling a full Napoleon and throwing off that balance of power.

For example, in the decades before the war, Germany’s military spending increased by 158%. But it wasn’t just them. Austria-Hungary’s increased by 160% and Britain’s by 117%. So why were they building these massive militaries? Imperialism. Another letter in the acronym.


Imperial powers needed a huge military to control their expanding borders and to keep order in places where they were now asserting full direct control, like in Africa. This is something that has happened forever in world history. The Romans needed more soldiers to control the newly conquered land. But they promised to pay their soldiers in land – so they then needed more land to make the new soldiers happy. And on and on.

And, unfortunately, the most common reason why empires fall is because they overextend themselves. It happened in the classical era with the Romans and the Han and it’s going to happen now with Europe.

Competition over land around the globe and looming militaries just on the other side of the border created tension across Europe. But also, it created a weird incentive to go to war. European powers saw that if they were to win a war against another major power, they would get their colonies. And, they all believed that if a war were to happen, their side would win easily because of those massive militaries I just talked about.

other motivations

Basically a lot of countries across Europe have something to prove. Austria wants to expand into the newly independent Balkans. France wants to get back land it lost to Germany in the Franco-Prussian War. The German Kaiser wants to prove his military strength and quash civil unrest at home thanks to a rising socialist movement.

And Russia is pretty embarrassed that it just lost a war to Japan and the czar also figures that a war might help let out some of the pent up anger and frustration amongst the peasants. Boy was he wrong about that one. It’s not that anyone openly wants war, but when the opportunity arises, a lot of countries will jump into war more quickly than they would have otherwise.


This plays into the last two letters from our MAIN causes of the war. Nationalism is reaching its global peak in the early 1900s. Thanks to centuries of unified nation-states and competition, plus an unfortunate dose of a “scientific” superiority complex, European states believe they are unstoppable. And they sort of are. If they would just not fight amongst themselves.

Again, it’s Survivor 101. If all the strong surfer dudes just made an alliance and stuck with it, they would make it to the end. But in walks Parvati with a rice bowl full of male ego to break everything up. Y’all really should be watching Survivor. It’s incredible.


All of this nationalistic sentiment, plus the tensions from imperial competition and huge threatening militaries, scares everyone into developing alliances. In the late 1800s countries start tying themselves together in the hopes that no one would ever risk going to war because it would mean dragging all of Europe into the fight. And it’s a good plan, if you are so egotistical that you forget about everyone except for the big guys. And they are. So they do.

But what they didn’t consider was a smaller actor who didn’t care about risking imperial landholdings or bringing down the European powerhouses. And in fact, to a little guy who is about to be conquered and subjugated, a world war might be just the thing he needs…

Enter: Gavrilo Princip.

crisis in the Balkans

First, where and what is Serbia? OK. Southeastern Europe is generally referred to as the Balkans. Today is makes up the countries of Albania, Bosnia, Bulgaria, Croatia, Macedonia (where Alexander the Great was from), and Serbia, among others. This region had been conquered by the Ottomans since the 1300s. But now that the Ottoman Empire is limping along, they have become independent by virtue of the Ottomans being the “sick man of Europe.”

But there’s another empire to the north, Austria-Hungary, that wants to grab up this land for itself. And they do. There is a fledgling country called Serbia that is trying to assert its independence, but the shadow of the Austro-Hungarian Empire is looming large. This is the remnants of the Holy Roman Empire, they’ve built up a massive industrialized military, and they have already started conquering places like Bosnia – which happens to have a large ethnic Serbian population that would like to be part of Serbia, please.

The Archduke visits Bosnia

Anyway, adding insult to injury, the Austrians send their heir to the throne, the Archduke Franz Ferdinand, to visit Bosnia on the day that commemorates the conquest of the Balkans by the Ottomans. Ouch.

Meanwhile, a group of Serbian nationalists or terrorists – depending on your perspective – has formed to fight against the Austrian empire. They’re called the Black Hand and they station multiple assassins along the parade route where Franz Ferdinand and his wife Sophie will drive in an open-topped car. Never a good idea.

The first assassin throws a bomb at the car but instead of landing inside, it bounces off the back and explodes seconds too late. People in the crowd were killed and injured but the Archduke got away. And that would have been that, except…

Sandwiches and the
assassination of franz ferdinand

Franz Ferdinand insisted on going to the hospital to visit those injured in the bombing. His security detail – who, frankly, must have not been very good at their jobs – try to convince him that he needs to leave Bosnia but he refuses. His limo is driving to the hospital when the driver gets lost. We’ll come back to them in a second.

Meanwhile, a 19-year-old named Gavrilo Princip is frustrated. He was stationed later on the parade route with a gun, but now he won’t get his chance. He thinks, “Ah screw it” and wanders back into the streets of Sarajevo. Some stories say that he went to a sandwich shop and was eating. I’m honestly not sure if that’s true, but for the sake of the story and our society’s mutual respect for the sandwich, let’s say it is.

Back to Franz Ferdinand. His driver is lost and trying to navigate the winding narrow streets in his limo. Trying to turn around, he backs the car into an alleyway and gets stuck. It smells good in the alleyway, they notice (probably). What’s that smell? Could it be the scent of freshly baked bread and delicious… sandwiches?

That’s right. Gavrilo Princip is inside and hears a commotion out in the alleyway. He walks out back and sees none other than the Archduke and heir to the Austrian throne sitting in an open-topped car. He holsters his sandwich, takes out his gun and shoots both Franz Ferdinand and his wife Sophie at point blank range. He tries to kill himself but is prevented by someone in the crowd who tackles him.

And then World War I happens.

A domino effect

Wait. What? Who cares about the Austrian heir and a tiny random place called Bosnia? If you answered, “No one except the Austrians and the Bosnians,” you are correct! Here’s what happens. Listen carefully…

The Black Hand was a Serbian nationalist organization so the Austrians blame the new nation of Serbia. They deliver an ultimatum that includes Serbia giving up its independence and becoming part of the Austro-Hungarian Empire. Serbia says, “No thank you.” So Austria declares war on Serbia.

But, Serbia has been talking to Russia. They’re like, “Hey Russia! We’re both Slavic people. Admit it – you always kind of hoped we would one day be part of your empire, right? I saw what you did in that Crimean War against the Ottomans… Don’t worry, we’re not mad. We were flattered. But you don’t want Austria to scoop us up first, do you?” So Russia steps in to defend Serbia.

But wait! Because Austria has its former Holy Roman Empire roommate: Germany. They want to make sure that in a war over eastern Europe, it’s them and their BFF who win, not Russia. And Germany has a plan…

Germany knows that Russia and France are allied. So they think it’s inevitable that France will get involved in the war. And Germany doesn’t want to be fighting a war on both sides of its borders – with Russia in the east and France in the west – that would be a terrible way to fight a war! (Side note: that’s exactly how both the world wars will be fought.) Germany looks around and thinks that France is the easier opponent of the two and so they scroll through their rolodex of military plans to ruin the 20th century and settle on the Schlieffen Plan.

Basically it goes like this: Germany will surprise invade France, win easily (because, you know, France) and then be able to turn around and fight Russia on one front. It’s foolproof! And what’s the quickest way to invade France? Through Belgium! So Germany invades France through the neutral country of Belgium. And who has promised to stay out of the war as long as no neutral countries are threatened? Britain for 100 points!

To recap: Austria declared war on Serbia who got help from Russia. Germany, stepping in to support Austria, declares war on Russia but also invades France (Russia’s ally). But they invade France through Belgium, who is protected by Great Britain. Oh and by the way, all of this happened in one week. Seven days.

So, in 1914, every major European power went to war over an archduke that only Austria really cared about. But, again, they all were tense because of imperial competition, fired up by nationalist sentiments, and overly confident with huge militaries. They all believed this war would last a few weeks. They all believed they would win. And they believed this would be the one last conflict to finally settle once and for all who was the best European. It would be the War to End All Wars.