Causes of World War I facts for kids

The First World War was a huge global conflict that lasted from 1914 to 1918. It started because of growing tensions between many countries. There were three main long-term reasons for the war: countries wanting to build empires, countries building up their armies and weapons, and countries forming secret alliances. The final event that sparked the war was the killing of Archduke Franz Ferdinand.

Why World War I Started

Countries Wanting More Land (Imperialism)

One big reason for World War I was that powerful countries wanted to create large empires. This idea is called imperialism. From the late 1800s, a country's power was often judged by how big its empire was.

Britain had the biggest empire, with many lands all over the world, like India. People used to say, "The sun never sets on the British Empire." This meant that because Britain owned land in so many different time zones, it was always daytime somewhere in their empire. This desire for more land and power led to competition and arguments between countries.

Building Up Armies and Weapons (Militarism)

To conquer and control lands far away, powerful countries built huge armies and navies. This focus on military strength is called militarism. Countries spent a lot of money very quickly to make their armed forces bigger and stronger.

In the early 1900s, Britain had the largest navy. This made their old rival, Germany, want to build a big navy too. When Britain launched a new, powerful warship called the Dreadnought, Germany quickly built its own version to keep up. This race to build more and better weapons created a lot of tension and made countries more ready for war.

Secret Friendships (Alliances)

The third long-term cause was alliances. The biggest countries in Europe formed two main groups. They were called the "Triple Entente" and the "Triple Alliance."

The Triple Entente included France, Great Britain, and Russia. These countries were worried about Germany's growing power. So, they promised to help each other if any one of them was attacked.

The Triple Alliance was made up of Germany, Austria-Hungary, and Italy. Germany didn't like being surrounded by France and Britain to the west and Russia to the east. So, Germany formed an alliance with Austria-Hungary and Italy to protect itself. These alliances meant that if one country went to war, its allies would join in, quickly making a small conflict much bigger.

The Spark: Archduke Franz Ferdinand's Assassination

The event that directly triggered World War I was the killing of Archduke Franz Ferdinand. He was next in line to become the emperor of Austria-Hungary. He was killed in Sarajevo on June 28, 1914. Both he and his wife, Countess Sophie, died.

They were visiting the capital of Bosnia. A secret group from Serbia, called the Black Hand, wanted Bosnia to break away from Austria-Hungary and become its own country. Russia supported this group.

The Archduke and his wife arrived by train and got into an open car. Members of the Black Hand knew their route. One of them threw a hand grenade at the car. It bounced off and injured people in the car behind them. The Archduke realized he was a target and decided to go to a hospital instead of continuing his trip.

However, his driver took a wrong turn and had to stop and reverse. By chance, the car slowed down right in front of Gavrilo Princip, a leader of the Black Hand. Seeing his chance, Princip fired his gun, killing the Archduke and Sophie, who was pregnant. Princip was arrested right away.

Austria-Hungary was furious that their future emperor had been killed. They blamed Serbia and attacked its capital, Belgrade. Serbia tried to surrender, but Austria-Hungary continued its attack.

Serbia's ally, Russia, then stepped in to defend Serbia. Soon after, Germany, an ally of Austria-Hungary, declared war on Russia. Germany also started moving its troops towards France, attacking Belgium on the way. France began preparing for a German invasion.

When Germany declared war on France, Britain then ordered Germany to stop attacking Belgium, which was a neutral country. When Germany didn't pull back from Belgium, Britain declared war on Germany. Finally, Austria-Hungary declared war on Russia, and the First World War officially began.

Images for kids

• 

  Map of the world with the participants in World War I in 1917. Allies in green, Central Powers in orange, and the neutral countries are in grey.

• 

  American cartoon showing territorial dispute between France and Germany over Alsace-Lorraine, 1898

• 

  French troops in Morocco, 1912

• 

  Mustafa Kemal (left) with an Ottoman military officer and Bedouin forces in Derna, Tripolitania Vilayet, 1912

• 

  Territorial gains of the Balkan states after the Balkan Wars

• 

  The Anglo-German naval arms race became a considerable source of tension between Germany and Britain prior to World War I. Royal Navy warships pictured above in battle formation.

• 

  World empires and colonies around 1914

• 

  "A Threatening Situation,", an American editorial cartoon depicting the supposed web of alliances. The caption reads, "If Austria attacks Serbia, Russia will fall upon Austria, Germany upon Russia, and France and England upon Germany." That dimension developed into the concept of chain ganging.

• 

  1909 cartoon in the American magazine Puck shows (clockwise) US, Germany, Britain, France and Japan engaged in naval race in a "no limit" game.

• 

  Louis P. Bénézet's map of "Europe As It Should Be" (1918), depicting imagined nations based on ethnic and linguistic criteria. It blamed German aggression on perceived threats to the traditional social order from radicals and ethnic nationalists.