How did nationalism lead to war?
Nationalism led to war by creating intense loyalty to one's nation-state that demanded territorial expansion, fueling competition between great powers for colonies and prestige, inspiring oppressed ethnic groups to seek independence through violence, and generating arms races and military buildups. It was a primary driver of both the German unification wars and World War I.
Nationalism — the belief that people who share a common language, culture, or ethnicity should form their own sovereign nation-state — was one of the most powerful and destructive political forces of the 19th and early 20th centuries. Its relationship with war was intimate and multifaceted.
Nationalism drove the unification wars that reshaped Europe's map. Italian unification (1859–1871) and German unification (1864–1871) were achieved through deliberate military campaigns. Otto von Bismarck orchestrated three wars — against Denmark, Austria, and France — to forge a unified German nation under Prussian leadership. These wars demonstrated that nationalism could be a weapon wielded by states to build power and that military victory could forge national identity.
Nationalism also fueled separatist movements that destabilized multi-ethnic empires. The Ottoman, Austro-Hungarian, and Russian empires all contained numerous ethnic groups that aspired to self-governance. The Balkans became 'the powder keg of Europe' as Serbian, Greek, Bulgarian, and Romanian nationalists fought for independence from Ottoman and Austrian rule. It was Serbian nationalism — specifically, the desire to unite all South Slavs under Serbian leadership — that produced the assassination of Archduke Franz Ferdinand and triggered World War I.
Imperial nationalism drove the great powers into global competition. The concept of national prestige demanded colonial empires, powerful navies, and international influence. The arms race between Britain and Germany — particularly the naval rivalry — was driven by nationalist publics who demanded that their nation be the most powerful. Newspapers, schools, and public ceremonies cultivated aggressive nationalism that made war seem glorious and necessary.
During World War I itself, nationalism sustained the fighting. Governments mobilized entire populations by appealing to national honor and survival. Propaganda demonized the enemy as a threat to national existence. The concept of 'total war' — in which entire nations mobilized for conflict — was a direct product of nationalist ideology. And the post-war peace settlement, which tried to redraw borders along national lines, created new grievances that would fuel the next conflict.
The irony of nationalism was that it promised self-determination and freedom for peoples but delivered competition, militarism, and catastrophic warfare between the nation-states it created. The nationalist fervor that unified Germany in 1871 led, through a chain of escalating rivalries, to the destruction of Europe in two world wars.