Causes of World War I

World War I began in the Balkans on 28 July 1914 and ended on 11 November 1918, resulting in 17 million deaths and 25 million injuries. Understanding why this huge conflict happened is still debated by historians today.

Scholars look at many long-term reasons, such as political and economic competition, growing armies, complicated alliances, and rising national pride. They also study shorter-term causes, like the decisions made during the tense weeks after the assassination of Archduke Franz Ferdinand of Austria by Gavrilo Princip, a Bosnian Serb nationalist supported by groups in Serbia. This event quickly led to a chain reaction involving many powerful nations.

The war followed years of diplomatic arguments among the Great Powers, including Italy, France, Germany, Britain, Austria-Hungary, and Russia, over European and world issues. These tensions built up because of shifting power balances in Europe since 1867. Historians still disagree about which countries and factors were most to blame for the outbreak of the war.

Immediate causes

Assassination of Archduke Franz Ferdinand by Serbian nationalists, 28 June 1914

Main article: Assassination of Archduke Franz Ferdinand

On 28 June 1914, Archduke Franz Ferdinand, who was next in line to become the leader of the Austro-Hungarian Empire, and his wife, Sophie, Duchess of Hohenberg, were sadly killed in Sarajevo. They were shot by Gavrilo Princip, who was part of a group of six people planning this act. This group was organized by Danilo Ilić, a member of a secret group called the Black Hand.

This event was very important because it made Austria-Hungary feel that their country was being threatened. Since Emperor Franz Josef was very old, many leaders in Austria believed that this act had to be answered with strong action.

Polarization of Europe, 1887–1914

In August 1914, a magazine described the assassination of Franz Ferdinand and his wife as a small reason for the big problems that followed. It talked about how the world’s money system was in trouble, trade had stopped, industries were struggling, and families were suffering. Millions of men in Europe had taken up weapons to fight each other.

The magazine said that most people involved in the conflict did not really want to fight each other. They were like two teams in a practice battle, but now the guns were loaded, and they had to fight. The only surprising thing about the war was when it started. No war in history had been talked about and prepared for so much before it happened. Every soldier knew where his uniform and rifle were stored and thought he knew where and when he would fight.

To understand why the war started in 1914, we need to see how countries formed two groups with shared goals and enemies. By August 1914, these groups were Germany and Austria-Hungary on one side, and Russia, France, and Britain on the other side.

German realignment to Austria-Hungary and Russian realignment to France, 1887–1892

In 1887, Germany and Russia made a secret agreement. But in 1890, a new leader in Germany decided to make a different agreement between Germany and Austria-Hungary instead. This happened because Russia was becoming more powerful in a region called the Balkans. Russia then made a strong military agreement with France. This was because Russia needed a friend after facing problems at home and losing money in Germany. This friendship between Russia and France lasted until 1917.

French distrust of Germany

Some reasons for World War I go back to an earlier war between France and Germany. Germany won and took away a part of France called Alsace-Lorraine. This made many people in France very unhappy, and they wanted to get it back. However, France eventually recovered and rebuilt its military. By the 1890s, France felt insecure next to the stronger Germany but still wanted to get Alsace-Lorraine back.

British alignment towards France and Russia, 1898–1907: The Triple Entente

After a leader in Germany left, France worked to make friends with Russia and Britain. Key moments were the Franco-Russian Alliance in 1894, the Entente Cordiale with Britain in 1904, and the Anglo-Russian Convention in 1907. These agreements led to the Triple Entente between Britain, France, and Russia. Britain also stopped being isolated and made agreements with France and Russia to protect its interests.

First Moroccan Crisis, 1905–06: Strengthening the Entente

The First Moroccan Crisis was a disagreement between March 1905 and May 1906 about Morocco. This crisis made Germany’s relations worse with France and Britain and helped strengthen the Entente Cordiale.

Bosnian Crisis, 1908: Worsening relations of Russia and Serbia with Austria-Hungary

In 1908, Austria-Hungary announced it would take over Bosnia and Herzegovina. This upset the balance of power in the Balkans and made Serbia and others very angry. Russia, though weak, still thought Austria-Hungary was being too aggressive.

Agadir crisis in Morocco, 1911

Imperial rivalries caused France, Germany, and Britain to compete for control of Morocco, leading to tension in 1911. France set up control over Morocco, which increased European tensions. Germany sent a ship to protest, deepening suspicions between Britain and Germany and bringing France and Britain closer together.

Italo-Turkish War: Isolation of the Ottomans, 1911–1912

The Kingdom of Italy fought the Ottoman Empire in North Africa from 1911 to 1912. Italy won and took over some areas, showing that no big power wanted to support the Ottoman Empire anymore. This led to more conflicts in the Balkans.

Balkan Wars, 1912–1913: Growth of Serbian and Russian power

The Balkan Wars were two conflicts in southeastern Europe in 1912 and 1913. Four Balkan states fought the Ottoman Empire and won, taking almost all its land in Europe. One of them, Bulgaria, lost to others later. These wars increased tensions between Russia and Austria-Hungary and made Serbia stronger, changing the balance of power in Europe.

Franco-Russian Alliance changes to Balkan inception scenario, 1911–1913

The original agreement between France and Russia was to protect each other from a German attack. But by 1911–1913, especially during the Balkan Wars, France changed its view. France now said it would support Russia if Austria-Hungary and Serbia went to war, making the Balkans very important for both countries.

Liman von Sanders Affair: 1913-14

This crisis happened when a German officer was appointed to lead troops near Constantinople. Russia objected strongly, seeing it as a threat. A compromise was made, but tensions remained.

Anglo-German détente, 1912–14

Historians say the earlier crises do not mean a European war was certain in 1914. In 1912, Germany cut its navy building, and in 1913, Britain and Germany agreed on some African lands. Relations improved, and by May 1914, a British diplomat noted that things were very calm.

Domestic political factors

Drivers of Austro-Hungarian policy

After the events of the July Crisis in 1914, Austria-Hungary explained its declaration of war on the Kingdom of Serbia as a way to protect itself. Historians say that the death of Franz Ferdinand was a key moment that helped turn the crisis into a larger war. Without him, there was less support for peace, and leaders made more aggressive decisions.

Some historians believe that Austria-Hungary’s leaders didn’t plan a big war at first. But once they were fighting Russia, they started to want more goals from the war. They disagreed about what those goals should be, especially about Poland.

Before the war, Austria-Hungary had many different groups of people who didn’t always agree. But the country was going through a time of strong economic growth, and most people felt happy with the government and its services.

German domestic politics

For more information: Fischer controversy

In Germany, some groups like the Social Democratic Party gained power in elections. The government was led by people from Prussia who worried about these changes. Some leaders thought that starting a war might distract people and gain support for the government. Others were worried that a war could cause big problems.

Drivers of Italian policy

See also: History of the Kingdom of Italy (1861–1946)

After Italy became a country, some Italian-speaking people were still living in places like Trentino-Alto Adige and Dalmatia, which were not part of Italy. This led to a movement wanting to bring these areas into Italy. Italy joined World War I in 1915 to try to complete its unity by taking these lands from Austria-Hungary.

Italy’s leaders had different ideas about the war. Some wanted to keep old alliances, while others saw a chance to gain land and support the country’s unity. After talks, Italy agreed to join the war and was promised lands with Italian speakers.

Drivers of Serbian policy

Serbia wanted to grow bigger after the Balkan Wars and dreamed of uniting areas with many Serbs living in them, including parts of Austria-Hungary. Serbia also wanted to be a leading country in the Balkans.

Serbia’s leaders had to balance between official policies and secret groups that wanted more aggressive actions. Russia supported Serbia, hoping it would focus its efforts against Austria-Hungary instead of competing with Bulgaria.

Imperialism

See also: New Imperialism

The world had almost no more space left for countries to expand into by around 1900. Every big country had reached the farthest it could go. This "global closure" made countries feel they had to compete more fiercely for power.

Countries like France, Britain, Russia, and Germany were trying to grow their influence around the world. This competition helped shape alliances and made some countries, like Germany, feel isolated. When countries tried to expand their power, it often led to tensions. For example, Germany wanted to build a railway from Berlin to Baghdad, which made other countries worry about their own influence.

Some people believed that countries went to war because businesses and banks wanted more resources and markets overseas. However, others think that leaders cared more about military strength and land than about money. In the end, these rivalries and feelings of isolation helped set the stage for bigger conflicts.

Social Darwinism

Main article: Social Darwinism

Social Darwinism was a theory that became popular in Europe between 1870 and 1914. It was based on ideas about how living things change over time, but applied to countries and groups of people. Many leaders believed that strong nations should compete and that only the strongest would survive. This idea encouraged Germany to become more powerful and to compete with countries like France and Britain.

Leaders in some countries believed that war was natural and even helpful. They thought it was better to fight when conditions were good rather than wait. Some even saw war as a way to make their country stronger. These beliefs made it harder to solve problems through talking and led to more conflicts between nations.

Arms race

By the 1870s to 1880s, all the major countries were getting ready for a big war, even though none really expected one to happen. Britain didn’t focus much on its small army but worked hard to build up its navy, which was already stronger than the next two biggest navies put together. Germany, France, Austria, Italy, Russia, and some smaller countries started systems where young men would spend a few years in the army and then many more years in a reserve group, training each summer. Men with higher status became officers. Each country made plans to quickly call up these reserves and send them to important places by train.

Every year, countries updated and made their plans more complex. They stored up weapons and supplies for armies that could be millions of people big. For example, Germany had 420,000 regular soldiers and 1.3 million reserves in 1874, but by 1897, that grew to 545,000 regular soldiers and 3.4 million reserves. France, Austria, and Russia also had millions of reserves. With changes in 1913, France increased its army size just before the war started. All the countries thought wars would be short, but the real war that began in 1914 turned into a long and tough fight.

Anglo-German naval race

Main article: Anglo–German naval arms race

Historians talk about how Germany’s building up of its navy affected the relationship between Britain and Germany. Germany never really caught up to Britain’s navy. With support from Wilhelm II, Grand Admiral Alfred von Tirpitz led efforts to build up Germany’s navy through four important laws between 1898 and 1912. From 1902 to 1910, Britain also expanded its navy to stay ahead of Germany. They focused on a new type of ship called the Dreadnought, launched in 1906, which was much stronger than others in Europe.

Britain’s big response showed Germany that catching up was very hard. By 1900, Britain’s navy was 3.7 times bigger in size than Germany’s; by 1910, it was 2.3 times bigger, and in 1914, 2.1 times bigger. Some think this big lead by Britain means the naval race wasn’t a main cause of the war. However, Germany had closed the gap by almost half, and Britain had a long goal of being stronger than any two enemies together. The US Navy was also growing, which made Germany’s progress seem more worrisome in Britain. In 1913, Britain had big debates about building new ships due to new ideas and money problems. In 1914, Germany decided to build submarines instead of new big ships, but kept this secret to avoid others doing the same.

Russian interests in the Balkans and the Ottoman Empire

Major Russian goals included making sure Saint Petersburg was seen as the protector of Eastern Christians in places like Serbia. Even though Russia was doing well economically and had a large army, its position was threatened by the growing Ottoman military, which was trained by German experts and had the latest technology. When the war began, Russia’s attention turned back to old goals: pushing the Ottomans out of Constantinople, extending control into parts of Anatolia and Persian Azerbaijan, and taking over Galicia. Controlling the Straits would have given Russia more power in the Black Sea and access to the Mediterranean.

Technical and military factors

Many leaders at the time thought the war might end quickly, but others knew it could last a long time and be very destructive. Military leaders believed it was important to strike first to gain an advantage. They made detailed plans for moving troops and equipment, often by train, on strict schedules.

These plans made it hard to use diplomacy because military leaders wanted to start moving troops as fast as possible. Once a country started its plans, it was hard to stop without causing big problems. This made it difficult to avoid war, as each side prepared quickly to defend itself.

Historiography

Main article: Historiography of the causes of World War I

Right after World War I ended, many historians from Britain and America thought Germany alone started the war. But later, in the 1920s and 1930s, historians began to blame all the countries involved more equally. German historians also disagreed with the idea that Germany was mainly to blame.

In the 1960s, a German historian named Fritz Fischer said that Germany’s leaders had actually wanted war. This caused big debates around the world about what Germany wanted long before the war. An American historian, Paul Schroeder, agreed that Germany did want more power but thought Fischer went too far in his ideas. Schroeder said Germany did want world power, but that wasn’t the main reason the war started in 1914. He believed there were many reasons, and any one of them could have started the war.

Today, historians still discuss who started the war and who is to blame. By the 1980s, many agreed that Germany had more responsibility than the other big countries, even if they didn’t all agree with Fischer’s exact ideas.