Nationalism as a Cause of World War I: A Detailed Summary

NationalismThe idea that people share an identity based on common values, beliefs, and cultural traditions, creating loyalty to their own nation. was one of the main causes of World War I, which began in July of 1914, following the assassination of Austrian Archduke Franz Ferdinand.  In fact, historians consider it to be one of four main long-term causes of the war, along with: militarism, alliance systems and imperialism.  Nationalism was a particularly important cause of World War I due to several key factors.  For instance, it caused nations to build up their armies and led to increased militarismThe buildup or expansion of a country’s military power and its ability to wage war..  As well, it created extremely high tensions in Europe in the decades before the outbreak of the First World War.  This was especially present during the Balkan Crisis before World War I.  Finally, nationalism was an important factor in why so many people volunteered for the war and fought on the front lines.

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What were the main effects of nationalism in Europe before World War I?

German and Italian UnificationGerman and Italian UnificationItaly unified as a country in 1861 and Germany in 1871, when smaller kingdoms joined into one. This gave millions of people a shared national identity for the first time.Balkan Resentment of EmpiresBalkan Resentment of EmpiresPeople in the Balkans resented control by the Ottoman and Austro-Hungarian Empires. They wanted sovereignty, the right to govern themselves, and pushed back against both powers.Bosnian Crisis of 1908Bosnian Crisis of 1908Austria-Hungary's annexation of Bosnia angered Serbia and raised tensions across the Balkans. It was one of the sharpest crises in the region before the war broke out.The Black Hand OrganizationThe Black Hand OrganizationThe Black Hand was a secret group that promoted Serbian and Slavic nationalism. Its members opposed foreign control of the Balkans and carried out acts of violence against that control, including arming the men who assassinated Archduke Franz Ferdinand.Arms Race Between France and GermanyArms Race Between France and GermanyNationalist rivalry pushed France and Germany to compete for military strength. Each country steadily expanded its army between 1870 and 1914 as distrust between them grew.Volunteering for the FrontVolunteering for the FrontNationalism gave millions of ordinary people a strong sense of duty to their country. This feeling was a key reason so many men volunteered to fight when war began in 1914.

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Nationalism in Europe Before World War I

The 19th century was a period of continuous change and competition in Europe.  Not only was it the height of European imperialism, but it also saw the rise of nationalism, which swept across the continent.  In general, nationalism is the idea that people identify with one another based on shared values, beliefs, and cultural traditions.  For instance, Italy formally unified as a country in 1861, and Germany did the same in 1871.  In both cases, smaller kingdoms unified into one larger country and saw the people of each country identify with each other nationalistically.  As such, nationalism played a significant role in carving up Europe between different groups of people.  This created situations in which certain nations disagreed and did not trust each other to an extremely high degree.  As well, some nations felt threatened by the nationalism of other nations, which led to several different crises.​

Every European nation experienced growth in nationalism in the lead up to the 1914 outbreak of World War I, but some experienced it more than others.  For example, the effects of nationalism were especially present in the Balkans and led to the Balkan CrisisA series of conflicts and tensions in southeastern Europe before World War I, including the Bosnian Crisis of 1908 and two Balkan Wars..

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One day the great European War will come out of some damned foolish thing in the Balkans.

Otto von Bismarck

Former German Chancellor, attributed remark

Bismarck was warning about the rising nationalist tensions in the Balkans, where local peoples resisted control by the Ottoman and Austro-Hungarian Empires. His prediction came true in 1914, when the assassination of Archduke Franz Ferdinand in Sarajevo became the spark that set off the Balkan Powder Keg and started World War I.

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Nationalism and the Balkan Crisis

The Balkan Crisis before World War I refers to the issues that existed in the Balkans in the years before the outbreak of World War I.  In short, this includes the Bosnian Crisis of 1908 and the two Balkan Wars (First Balkan War and Second Balkan War) which took place in 1912 and 1913.  These events were significant because they led to the eventual 1914 outbreak of World War I.​

The Balkans is the term for the southeastern region of Europe.  This area included countries such as: Serbia, Greece, Montenegro and Bulgaria.  However, in the decades before World War I, both the Ottoman Empire and Austro-Hungarian Empire had considerable influence in the region of the Balkans.  The people of the Balkans did not appreciate this and actively fought back against the nationalistic pressure from both empires.  In fact, the First Balkan War was a direct result of the anger that the Balkan nations had for the Ottoman Empire.​

Historians consider the nationalistic tensions that existed in the Balkans in the early 20th century as an important factor in the eventual outbreak of World War I.  In fact, the term ‘Balkan Powder Keg’ was used to describe the crisis in the Balkans before World War I.  In general, the term is a metaphor and compares the nationalistic tensions present in the Balkans before World War I to that of a keg (or barrel) of gunpowder, which is essentially a bomb.  Thus, the only thing the powder keg needed to explode was a spark, which was the assassination of Austrian Archduke Franz Ferdinand on June 28th, 1914.​

Austria blamed Serbia for the assassination, since Ferdinand was murdered by Gavrilo Princip – a Bosnian Serb nationalist who had been armed and trained by the Black HandA secret organization aimed at promoting Serbian and Slavic nationalism that armed and trained the men who assassinated Archduke Franz Ferdinand..  The Black Hand was a secret organization aimed at promoting Serbian (and Slavic) nationalism, and helped plan the assassination of Ferdinand in protest of Austria’s influence in the Balkans.  As such, this displays that World War I was a direct result of the growth of Balkan nationalism.​

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Why did Austria blame Serbia for the assassination of Archduke Franz Ferdinand?

Tap an option.

Franz Ferdinand was shot by a Serbian army general acting on public orders from the Serbian kingGavrilo Princip had been armed and trained by the Black Hand, a secret group that promoted Serbian nationalismSerbia had formally declared war on Austria-Hungary a week before the assassinationFranz Ferdinand was shot inside Serbia while on a diplomatic visit to Belgrade

ExplanationGavrilo Princip was a Bosnian Serb nationalist who had been armed and trained by the Black Hand, a secret group tied to officers in the Serbian army. Austria-Hungary believed Serbia stood behind the plot and held it responsible for the killing in Sarajevo.

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Nationalism and Militarism Before World War I

Militarism can best be understood as the buildup or expansion of the ability of a country’s military to wage war.  In the decades before World War I many European countries began to practice militarism and worked to expand and strengthen their military forces.  Nationalism led to this situation because it was responsible for pushing countries to expand their influence in Europe.  This caused tensions between the major powers of Europe.  For example, there was an intense arms raceA competition between countries to rapidly grow and strengthen their military forces to outmatch each other. and naval race between several European nations in the buildup to World War I.  Specifically, France and Germany were heavily involved in an arms race in which each country steadily expanded its army between 1870 and 1914.  Both nations had a history of war against each other and their rivalry caused them to expand their military forces.

By the outbreak of fighting in 1914, France and Germany could each call up millions of trained soldiers.  The buildup of these armies was directly related to nationalism because each nation was compelled to protect itself amid the growing nationalistic tensions of the time.  Ultimately, the arms race showed the distrust between the nations of Europe and when World War I began in 1914 it allowed the countries to go to war more easily. 

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Surprising Fact

In 1913, France passed the Three-Year Law, which stretched required military service for young men from two years to three.

French leaders argued the change was needed to keep pace with the growing German army across the border. Germany passed its own army law the same year to add more soldiers. Both laws showed how nationalist rivalry pushed Europe toward war.

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How Did Nationalism Cause World War I?

As shown by the information above, nationalism played a very significant role in the eventual outbreak of World War I.  This is because it caused tensions and unrest to grow in certain parts of Europe.  For example, the Austro-Hungarian Empire was not made up of one single nation, but rather consisted of many different groups.  Many of these groups sought to have control over themselves and wanted sovereigntyThe right of a group or nation to govern and control itself rather than be ruled by another power. from the rule of the Austro-Hungarian Empire.  This created a great deal of unrest in the empire.  This was especially apparent in the Balkans, which underwent the events of the Balkan Crisis and what historians refer to as the ‘Balkan Powder KegA metaphor comparing the explosive nationalistic tensions in the Balkans before World War I to a barrel of gunpowder needing only a spark.’.​

Ultimately, the assassination of Austro-Hungarian Archduke Franz Ferdinand in June of 1914 was the spark that lit the match of the Balkan Powder Keg and plunged Europe into World War I.  Nationalism as a movement in Europe in the years before World War I created the tensions necessary for a small event like the assassination of Franz Ferdinand to explode into the worldwide conflict that it became.

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The eventNationalism in the Austro-Hungarian Empire before World War I

Tap each impact to read what it led to.

1Demand for Self-Rule2Growth of Separatist Movements3Bosnian Crisis of 19084Assassination of Franz Ferdinand5Austria-Hungary's Ultimatum to Serbia

Demand for Self-RuleThe Austro-Hungarian Empire contained many ethnic groups, including Czechs, Slovaks, Poles, Croats, Serbs, and Romanians. Each group wanted sovereignty, the right to govern itself, rather than remain under Austrian control.

Growth of Separatist MovementsNationalist groups inside the empire actively organized to resist Austrian rule. In Bosnia, young Serb nationalists found support from the Black Hand, a secret organization in Serbia that promoted Serbian and Slavic nationalism.

Bosnian Crisis of 1908Austria-Hungary formally annexed Bosnia in 1908, angering Slavic nationalists who saw Bosnia as part of a South Slavic homeland. The crisis deepened hostility between Austria-Hungary and Serbia and brought both countries close to open conflict.

Assassination of Franz FerdinandGavrilo Princip, a Bosnian Serb nationalist, killed Archduke Franz Ferdinand in Sarajevo on June 28th, 1914. The killing was a direct protest against Austria-Hungary's control over Slavic peoples in the Balkans.

Austria-Hungary's Ultimatum to SerbiaAfter the assassination, Austria-Hungary issued a harsh ultimatum to Serbia in late July of 1914, holding Serbia responsible for the attack. Serbia's partial refusal triggered a chain of events that pulled the alliance systems of Europe into World War I.

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MLA: Beck, Elias. “Nationalism as a Cause of World War I: A Detailed Summary.” HistoryCrunch, 28 September 2026, https://historycrunch.com/nationalism-as-a-cause-of-world-war-i/.

APA: Beck, E. (2026). Nationalism as a Cause of World War I: A Detailed Summary. HistoryCrunch. https://historycrunch.com/nationalism-as-a-cause-of-world-war-i/

Chicago: Beck, Elias. “Nationalism as a Cause of World War I: A Detailed Summary.” HistoryCrunch. September 28, 2026. https://historycrunch.com/nationalism-as-a-cause-of-world-war-i/

Sources

• Hew Strachan, The First World War.
• Fordham Modern History Sourcebook
• Margaret MacMillan, The War That Ended Peace.