Causes of WWI

In June 1914, Franz Ferdinand, the archduke and heir to the Austro-Hungarian Empire, was assassinated in Bosnia. By mid-August, all of the European powers had been drawn into a war.

How did a regional conflict spark a World War? To understand the main causes of World War I in Europe, it's important to look at the sources of increasing tensions in Europe in the years before the war as long term causes of WWI then trace how the assassination of the archduke sparked a general war.

Main Causes of World War I

The main causes of World War I can be summarized in the following list of broad factors:

• Imperialism and Militarism
• Nationalism
• Conflict in the Balkan Region
• The Alliance System
• The Assassination of Franz Ferdinand

These factors worked together to provoke a larger conflict when a war broke out between Austria-Hungary and Serbia. It's useful to further consider them in terms of long term causes of WWI and the immediate events that sparked the war before finally considering why the US entered the conflict.

Long Term Causes of World War I

The main causes of World War I listed above all contributed to the tensions that sparked the war.

Imperialism and Militarism as Cause of World War I

It's important to first consider the role of imperialism and militarism as cause of WWI.

Industrialization Leads to Imperial Conquest and Rivalry

The period before the war had seen the rapid expansion of European empires in Africa and Asia. Imperialism in this period was driven by industrialization. European powers sought the control of raw materials and markets for finished goods.

France and Britain built the largest empires. Meanwhile, Germany wanted a larger empire. There were two crises over Morocco in 1905 and 1911, both of which had enflamed tensions between Britain and France on one hand and Germany on the other.

Militarism and the Arms Race

In the years leading up to the war, all the countries of Europe increased the size of their militaries. A further naval race ensued between Britain and Germany. Each sought to have the largest and most powerful navy.

The Arms Race created a vicious cycle. Each side felt the need to further increase the size of their militaries in response to each other. Larger and more powerful militaries increased tensions and made each side more confident they could win a war.

Nationalism

Nationalism helped to fuel the imperial competition. Countries saw more colonies as a sign of more power. Nationalism also promoted militarism. Nationalists took pride in having a strong military.

Rise of Germany

Germany did not exist as a formal nation state but a loose confederacy of independent states before 1870. These states united behind Prussia during the 1870-71 Franco-Prussian War. A new German Empire was declared after victory in that war. Forged in conflict, militarism became a key part of German nationalism.

Germany quickly industrialized. By 1914, it had the largest army, and its steel production had even surpassed Britain's. Increasingly, the British saw Germany as a threat to be reckoned with. In France, a desire for revenge for the 1871 humiliation further fueled tensions.

Conflict in the Balkans

Nationalism played a different role in fueling tensions in the Balkans region. This area had a mix of ethnic groups that had been long under the control of Austria-Hungary or the Ottoman Empire. Many of them now wanted to be independent and rule themselves.

Tensions were particularly high between Serbia and Austria-Hungary. Serbia had only formed as an independent state in 1878, and it won a series of wars in 1912-13 that allowed it to expand its territory. Austria-Hungary, made up of a variety of ethnic groups and nationalities, including Serbs, saw it as a threat.

Conflict had arisen specifically over the status of Bosnia. Many Serbs lived here, and Serbian nationalists hope to include it as part of a larger Serbia. However, in 1908, Austria-Hungary annexed it. It would be the status of Bosnia that lit the spark of the war.

Fig 1 - Cartoon showing the Balkans as the powder keg of Europe.

The Alliance System

Another one of the main causes of World War I in Europe was the Alliance System. This system had been conceived as a deterrent to war by the German Chancellor Otto von Bismarck. Fearing a possible future war with rival France, he had sought to align Germany with Austria-Hungary. Italy also joined this alliance, creating the Triple Alliance of Germany, Austria-Hungary, and Italy.

Meanwhile, both Britain and France grew increasingly wary of Germany. They announced the Entente Cordiale, or friendly agreement, in 1905. Russia saw itself as a protector of Serbia, which brought it into conflict with Austria-Hungary, while France saw an alliance with Russia as a way to contain Germany. The Triple Entente was the alliance of Britain, France, and Russia.

This Alliance System divided Europe into two competing camps. It meant countries who did not have a direct conflict, such as Germany and Russia, saw each other as rivals. The alliances ensured that a war would not be fought between just two countries but would embroil all of them.

Fig 2 - Map of the Alliances before World War One.

The Immediate Causes of World War I in Europe

All of the above long term causes of World War I combined with events in 1914 to make a regional conflict between Serbia and Austria-Hungary grow into a broader war.

The Assassination of Franz Ferdinand

Franz Ferdinand was the archduke and heir to the Austro-Hungarian Empire. In June 1914, he visited Sarajevo, the capital of Bosnia.

Serb nationalists plotted and carried out his assassination on June 28, 1924. Austria-Hungary blamed the Serbian government for the assassination. Austria-Hungary declared war on Serbia on July 28, 1914, one month to the day after the assassination.

Alliances Cause a Regional War to Broaden

The invasion of Serbia by Austria-Hungary set in motion the activation of the Alliance System.

Russia Mobilizes

First, Russia mobilized its army in support of Serbia. As their mobilization plans had considered that war with Austria-Hungary would also mean war against Germany, their armies mobilized on Germany's border as well.

In a series of telegrams between Russian Tsar Nicholas II and German Kaiser Wilhelm II, each side expressed their desire to avoid war. However, the Russian mobilization made Wilhelm feel compelled to mobilize his own armies.

Germany Activates its War Plans

The Germans were now faced with a decision. Much like Russia, their war mobilization plans were based on an assumption that war with Russia would also mean war with France.

A key factor in German war planning was the desire to avoid a two front war fighting France to the West and Russia to the East at the same time. Therefore, the German war plan, called the Schlieffen Plan, counted on a quick defeat of France by invading through Belgium. After defeating France, the German armies could focus on fighting Russia.

After the French refused to promise neutrality in a war between Germany and Russia, the Germans decided to activate the Schlieffen Plan, declaring war on France and Belgium.

Britain Joins the Fray

Britain responded by declaring war on Germany.

The Alliance System had turned a war between Serbia and Austria-Hungary into a much larger one between Austria-Hungary and Germany, called the Central Powers, on one hand and Russia, France, Britain, and Serbia, called the Allied Powers, on the other.

The Ottoman Empire would later join the war on the Central Powers' side, and Italy and United States would join on the Allied Powers' side.

Fig 3 - Cartoon showing the chain reaction starting World War One.

Causes of US Entry into WWI

There are several causes of US entry into WWI. US President Woodrow Wilson originally declared neutrality. However, the US was eventually drawn into the war.

Relations with Britain and France

The US had a close relationship with Britain and France as allies and trade partners. US banks made large loans to the Allies at the start of the war and the US also sold arms to them.

Furthermore, public opinion in the United States was sympathetic to their cause. Germany was seen as a threat to democracy and reports of German atrocities in Belgium led to calls for intervention.

The Lusitania and Zimmerman Telegrams

More direct tensions with Germany emerged during the war and were also important causes of US entry into WWI.

German U-Boats, or submarines, were highly successful at targeting Allied shipping. The Germans practiced a policy of unrestricted submarine warfare, which meant that they frequently targeted non-military vessels.

One such target was the RMS Lusitania. This was a British merchant ship that was carrying passengers in addition to armaments. On May 7, 1915, the ship was sunk by a German U-Boat. There were 128 American citizens on board, and outrage about the attack was one of the key causes of US entry into WWI two years later.

Another was the Zimmerman Telegrams. In January of 1917, the German Foreign Secretary Arther Zimmerman sent a secret message to the German embassy in Mexico. In it, he proposed an alliance between Germany and Mexico, where Mexico could reclaim the land previously lost to the United States in the event that the US entered the war.

The telegram was intercepted by the British, who turned it over to the US. It sparked national outrage when published in newspapers that March. US entry into WWI followed shortly in April 1917.

1. Wilhelm II. Telegram to Tsar Nicholas II. July 30, 1914.

2. Woodrow Wilson. Speech before Congress asking for declaration of war. April 2, 1917.