Was nationalism a cause of WWI?

Yes, nationalism was a significant cause of World War I. It fueled intense competition and rivalries between nations, particularly in Europe, as countries sought to assert their dominance and promote their national interests. Nationalistic fervor often led to conflicts over territories and ethnic tensions, exemplified by the assassination of Archduke Franz Ferdinand, which was driven by nationalist sentiments in the Balkans. This environment of heightened nationalism contributed to the alliances and hostilities that ultimately triggered the war.