What event led to the War of Spanish Succession?

The event that led to the War of Spanish Succession was the decision of Charles II of Spain to name Louis XIV's grandson as his heir. This choice alarmed other European powers, particularly because it threatened to unite the powerful Bourbon thrones of France and Spain under a single ruler. Such a union was seen as a significant imbalance in power that could upset the existing political and territorial configurations in Europe.

The reaction to this potential consolidation of Bourbon power spurred a coalition of various nations, including England, the Dutch Republic, and Austria, who were concerned about the dominance of France and its allies. This coalition ultimately led to military conflict, as those nations sought to prevent France from becoming too powerful by securing a separate succession for the Spanish throne. Thus, Charles II's will became the catalyst for the broader conflict known as the War of Spanish Succession, which aimed to resolve the issue of succession and maintain the balance of power in Europe.