The main cause of the First World War, which began in 1914, was a complex interplay of factors, including nationalism, militarism, imperialism, and a system of alliances. The assassination of Archduke Franz Ferdinand of Austria-Hungary in June 1914 acted as a catalyst, triggering a series of diplomatic crises. The existing alliances pulled multiple countries into the conflict, with the Central Powers (Germany, Austria-Hungary, and later the Ottoman Empire) facing off against the Entente Powers (France, Russia, and the United Kingdom). The war ultimately led to unprecedented devastation and redefined international relations and warfare.