Which factor is most commonly identified as a major driver of World War I?

• A. Global warming
• B. The jazz age
• C. Space exploration
• D. Nationalism

Answer: (D)

Nationalism is the major driver at the heart of World War I. A powerful belief in the primacy of the nation and national destiny created intense rivalries, distrust, and a sense that a nation's interests justified taking aggressive measures. In Europe, nationalistic fervor fed ambitions for greater power, unification, and self-determination, making states more willing to mobilize and confront rivals rather than seek peaceful accommodation. This was especially evident in the Balkans, where diverse ethnic groups sought independence or union with their national cores, destabilizing multiethnic empires like Austria-Hungary and pulling in neighboring powers that championed or feared nationalist movements. When a nationalist-tinged assassination occurred, the existing rivalries and alliance commitments transformed a regional crisis into a global conflict. The other options don’t fit the historical dynamics of 1914: global warming, a distant concern for that era; the jazz age, a cultural development that came after the war; and space exploration, nonexistent as a factor at that time.