In the aftermath of the assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by Gabriel Princip in Sarajevo on June 28, 1914, tensions escalated between Austria-Hungary and Serbia. The Austro-Hungarian government issued a complex ultimatum to Serbia, which contained ten demands, on July 23, 1914. Although Serbia accepted most of the demands, it rejected key points that would infringe upon its sovereignty. This response fueled Austria-Hungary’s ire and led them to perceive Serbia as a significant threat. Consequently, on July 28, 1914, Austria-Hungary declared war on Serbia, triggering a chain reaction of alliances and treaties that had been established between various European powers. Russia, an ally of Serbia, began mobilization efforts, while Germany, allied with Austria-Hungary, extended support. France and the United Kingdom were drawn in as their alliances with Russia prompted them to act.

This declaration of war set off a domino effect, as countries rapidly mobilized and declared war on one another, culminating in a truly global conflict. The July Crisis illustrated the fragility of peace in Europe, and the failure of diplomatic efforts to resolve the situation without resorting to war. Within weeks, Europe was engulfed in what would become known as World War I, characterized by trench warfare and unprecedented levels of destruction. The conflict dramatically altered the political landscape of Europe and had far-reaching consequences around the globe, including the eventual emergence of new nations and ideologies.