On this day in 1914 Gavrilo Princip assassinated the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife, Sophie, on the streets of Sarajevo. Princip and his co-conspirators were recruited and organized by the “Black Hand,” an organization headed by the Chief of Serbian Military Intelligence.
The Austro-Hungarian empire responded with an ultimatum to the government of the Kingdom of Serbia. The demands made in this ultimatum were impossible for the government of Serbia to meet (likely by design), and so after a month of desperate diplomatic wrangling and confusion between the great powers, the Empire declared war on July 28. Russia, as protector of the Slavic people and unwilling to see the Empire expand its power in what was viewed as Russia’s sphere of influence, began to mobilize.
A day later, Germany began to mobilize in support of their Austrian allies and in anticipation of the intervention of Russia’s ally, France. Germany invaded Belgium on August 2 as part of their planned outflanking of the French, and two days later Great Britain declared war on Germany in response to their violation of Belgian neutrality. The Great War had begun.
It is darkly amusing in hindsight that Franz Ferdinand was unpopular with the government of his uncle, Emperor Franz Joseph I, partly on the grounds that he favored a more cautious approach to the Empire’s relations with Serbia.