What event is considered the immediate trigger of World War I in 1914?

• A. The assassination of Archduke Franz Ferdinand in Sarajevo
• B. The invasion of Belgium
• C. The Bolshevik Revolution
• D. The sinking of the Lusitania

Answer: (A)

The immediate trigger of World War I was the assassination of Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, in Sarajevo on June 28, 1914. His murder by Gavrilo Princip provided Austria-Hungary with a pretext to move against Serbia, setting off a chain reaction through Europe’s tension-filled alliance system. Austria-Hungary’s ultimatum to Serbia, Serbia’s reply, and the subsequent declarations of war pulled in Russia, Germany, France, and eventually Britain as mobilizations and alliances activated one after another. In short, the assassination created the spark that ignited a broader conflict, while other events like the invasion of Belgium, the Bolshevik Revolution, or the sinking of the Lusitania occurred after the war had already begun or later in its course.