The roots of this military conflict can be traced to the assassination of Archduke Franz Ferdinand of Austria on June 28, 1914, which prompted Austria-Hungary to issue an ultimatum to Serbia. Serbia's response was seen as inadequate, leading Austria-Hungary to declare war on Serbia on July 28, 1914. Serbia's alliance with Russia set off a series of mobilizations and declarations of war across Europe. By early August, tensions escalated rapidly as nations began to take sides in what would soon become World War I. On August 6, Serbia took the formal step of declaring war on Germany, who had declared war on Russia earlier in the week, while Austria-Hungary simultaneously declared war on Russia. This marked a significant turning point as both sides began to mobilize for what would become one of the largest and deadliest conflicts in history. The declarations were emblematic of a tangled network of alliances and enmities in Europe, creating a chain reaction that would engulf numerous nations and lead to vast devastation across the continent.