The primary cause of the outbreak of World War I can be traced to a complex interplay of factors, predominantly the assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914. This event sparked a series of diplomatic crises and alliances, leading to heightened tensions among European powers. Factors such as militarism, imperialism, and nationalism further fueled rivalries, creating a precarious situation where a localized incident escalated into a global conflict. The entangled alliances (Triple Alliance and Triple Entente) meant that a conflict involving one nation quickly involved many others, igniting a devastating war.