What major global conflict was sparked by the assassination of Archduke Franz Ferdinand?

The assassination of Archduke Franz Ferdinand in June 1914 is widely recognized as the immediate catalyst that set off a chain of events leading to World War I. The archduke was the heir to the Austro-Hungarian throne, and his assassination by a Bosnian Serb nationalist ignited existing tensions among the major powers of Europe, which were already embroiled in a complex web of alliances and rivalries.

Following the assassination, Austria-Hungary issued an ultimatum to Serbia, which was only partially accepted. This rejection prompted Austria-Hungary to declare war on Serbia. The alliance system in place caused other nations to quickly become involved. Russia mobilized in defense of Serbia, leading Germany to declare war on Russia, and soon after on Russia's ally, France. The conflict escalated further when Germany invaded Belgium, prompting Britain to enter the war. This sequence of alliances and declarations of war rapidly spiraled into a global conflict.

This context underlines why World War I is directly linked to the assassination of Franz Ferdinand, distinguishing it from World War II, the Korean War, or the Vietnam War, which stem from different causes and were influenced by various geopolitical factors occurring much later in the 20th century.