What main causes did nationalism have on world war 1?

Nationalism significantly contributed to the outbreak of World War I by fostering intense rivalries among European nations, leading to an arms race and the formation of hostile alliances. Ethnic groups within empires, such as the Austro-Hungarian and Ottoman Empires, sought independence, creating tension and conflict. Nationalist fervor also fueled militarism, as countries prioritized military strength to assert their national interests. Ultimately, these factors created an environment ripe for conflict, culminating in the war following the assassination of Archduke Franz Ferdinand.