What was the immediate effect of the assassination of Archduke Franz Ferdinand?

The assassination of Archduke Franz Ferdinand on June 28, 1914, was a pivotal moment in history that set off a chain reaction leading to one of the largest and most devastating conflicts, World War I. Following the assassination, tensions among the major European powers, already heightened due to nationalistic rivalries and complex alliances, escalated rapidly. Austria-Hungary's declaration of war against Serbia, where the assassination was plotted, activated a series of alliances and obligations among countries.

Russia mobilized to support Serbia, Germany declared war on Russia in defense of Austria-Hungary, and soon after, other nations were drawn into the conflict due to pre-existing treaties and alliances. This rapid escalation led to the declaration of war, marking the official onset of World War I in July 1914. Thus, the immediate effect of the assassination was not just an isolated incident but a catalyst for a larger global conflict involving numerous nations and resulting in extensive loss of life and geopolitical upheaval.

The other options reflect events that occurred in different contexts and time periods, making them irrelevant to the immediate aftermath of the assassination. NATO was formed after World War II, the Bolshevik Revolution occurred in 1917, and the Cold War developed post-