Today we’re going to tell you one of the most striking “butterfly effect” stories in world history — the story of how two bullets fired by a 19-year-old, who found his chance in front of a car that took a wrong turn, ended up starting a war that would kill more than 17 million people.
June 28, 1914. A sunny summer day. The streets of Sarajevo had a festive mood. No one that day knew that Europe’s bloodiest century was about to begin.
A Crown Prince’s Visit

Archduke Franz Ferdinand, heir to the throne of the Austro-Hungarian Empire, was visiting Sarajevo together with his wife Sophie. At the time, Bosnia-Herzegovina was under Austro-Hungarian administration, a situation that deeply angered Serb nationalists in the region.
A group of young men belonging to the secret organization “Young Bosnia” had been preparing for months to assassinate Franz Ferdinand.
In the morning, as the motorcade moved through the city, an assassin threw a bomb. The bomb missed its target but struck one of the vehicles, injuring several people. Franz Ferdinand wanted to go to the hospital to visit the wounded. It was this very act of humanity that would lead him to his death.
A Small Wrong Turn, an Enormous Consequence
As the motorcade headed to the hospital, the driver mistakenly turned onto the old route. The governor immediately warned, “we’re on the wrong road,” and the driver stopped the car to try to reverse. At that very moment, young Gavrilo Princip, who hadn’t left the area since the morning’s assassination attempt, suddenly found himself right next to the car.
He fired two shots. One bullet struck Franz Ferdinand, the other struck his wife Sophie. Both died shortly after.

But What If the Driver Hadn’t Taken a Wrong Turn?
Let’s pause and think for a moment. If the driver had taken the correct route that day, Princip probably wouldn’t have gotten the chance to strike. Historians still refer to this moment today as “history’s most expensive wrong turn.”
From a Bullet to a Continental War: The Chain of Cause and Effect
So how did a single assassination turn into a whole world war? Let’s trace the chain reaction step by step:
- Austria-Hungary believed Serbia was behind the assassination and issued Serbia an ultimatum with harsh terms.
- Serbia did not accept one clause of the ultimatum. Austria-Hungary deemed this sufficient and declared war on Serbia on July 28, 1914.
- Russia, an ally of Serbia, began mobilizing its army.
- Germany, an ally of Austria-Hungary, declared war on Russia, then on Russia’s ally France.
- Germany’s attack on France through Belgium also drew Britain, which had guaranteed Belgium’s neutrality, into the war.

As you can see, a system of alliances chained to one another allowed a single spark to quickly turn into a continent-wide blaze. A few months later, the Ottoman Empire also entered the war alongside Germany, and the conflict truly took on a global scale.
A Little-Known Fact
Gavrilo Princip was only 19 years old at the time of the assassination, and under Austro-Hungarian law, criminals under 20 could not be sentenced to death. So Princip was not executed; instead he was sentenced to 20 years in prison. But he never lived to see the war end, dying in prison of bone tuberculosis. He never found out how the war he had started actually ended.
The War’s Echo Today
By the end of World War I, four great empires (the Ottoman, Austro-Hungarian, Russian, and German empires) had vanished from history. The current borders of the Middle East were drawn through secret agreements signed after the war. In other words, many of the borders we see on the map today can, in fact, be traced all the way back to those two bullets fired in Sarajevo that June morning.
Frequently Asked Questions
The assassination was carried out by Gavrilo Princip, a Bosnian Serb nationalist belonging to the “Young Bosnia” organization.
No. The assassination was the direct pretext for the war, but the underlying cause was the system of alliances, the arms race, and colonial rivalries in Europe. Even without the assassination, some other event would most likely have triggered the war.
The Ottoman Empire entered the war alongside Germany about four months after the assassination, in October 1914.
Because he was 19 years old, he was not executed and instead received a 20-year prison sentence. He died of tuberculosis in prison in 1918, before the war ended.
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