Which major world event was triggered by the assassination of Archduke Franz Ferdinand?

The assassination of Archduke Franz Ferdinand on June 28, 1914, serves as a pivotal trigger for World War I, marking the beginning of a complex chain of events that escalated tensions across Europe. The Archduke was the heir to the Austro-Hungarian throne, and his assassination by a nationalist from Serbia intensified existing rivalries among the major powers.

Following the assassination, Austria-Hungary issued an ultimatum to Serbia, which contained several demands that were intentionally harsh. Serbia's response was deemed unsatisfactory, leading Austria-Hungary to declare war on Serbia. This conflict quickly garnered the attention of other nations due to a web of alliances and treaties. Russia mobilized to support Serbia, Germany declared war on Russia, and soon multiple countries joined the fray, leading to a full-scale global conflict.

In stark contrast, the other events listed—World War II, the Cold War, and the Korean War—were the outcomes of different historical circumstances and did not directly relate to the events surrounding the assassination of Franz Ferdinand. Understanding this specific event illuminates how nationalistic tensions and political alliances in early 20th-century Europe culminated in a war that reshaped world history.