Final answer:
The assassination of Archduke Franz Ferdinand triggered World War I, leading to a chain reaction of declarations and entangling major powers in a global conflict.
Explanation:
The assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914 was the immediate trigger for World War I. This event led Austria-Hungary to declare war on Serbia, causing a chain reaction of declarations involving various alliances and escalating into a global conflict.
Germany, Austria-Hungary, and the Ottoman Empire formed the Central Powers, while Britain, France, and Russia formed the Allied Powers, entangling the entire continent in warfare.
The war was also fueled by geopolitical ambitions, rising nationalism, and a complex web of military alliances that set the stage for the Great War to spread across Europe.
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