How did nationalism cause conflict between nations during world war 1?

Nationalism fueled intense rivalries and aspirations for independence among various ethnic groups in Europe, leading to heightened tensions between nations. Countries like Serbia sought to unify Slavic peoples, which threatened Austria-Hungary's stability and led to conflicts. The competition for dominance and colonial territories further exacerbated these nationalist sentiments, ultimately contributing to the outbreak of World War I after the assassination of Archduke Franz Ferdinand. Nationalism not only ignited existing tensions but also made diplomatic resolutions more difficult, pushing nations towards war.