The major conflict sparked by the assassination of Archduke Franz Ferdinand was World War I. The event occurred on June 28, 1914, when the heir to the Austro-Hungarian throne was killed by Gavrilo Princip, a member of the nationalist group known as the Black Hand. This assassination set off a chain reaction of events, leading Austria-Hungary to declare war on Serbia, which escalated due to existing alliances between major European powers. As countries mobilized their forces, the conflict expanded, drawing in nations worldwide and resulting in unprecedented loss of life and a reshaping of global politics that would echo for decades, culminating in further conflicts.