What was a significant long-term cause of World War I?

Nationalism was a significant long-term cause of World War I because it fostered a sense of superiority and competition among nations. In the years leading up to the war, various ethnic groups sought independence and national recognition, while established nations pushed to assert their dominance. This pervasive sense of nationalism created tensions, particularly in regions like the Balkans, where multiple ethnic groups were vying for self-determination and political power.

Additionally, nationalism contributed to the formation of alliances, as nations aligned themselves with others that shared similar ethnic or cultural backgrounds. It also stoked militaristic ambitions, as countries bolstered their military capabilities in part to protect national interests and assert their power on a global scale. The assassination of Archduke Franz Ferdinand, which was supported by nationalist sentiments in Serbia, served as a catalyst that ignited these existing tensions into a broader conflict, ultimately leading to World War I.