What describes an important cause of World War 1?

An important cause of World War I was the complex system of alliances that developed in Europe, which created a web of obligations among nations. The assassination of Archduke Franz Ferdinand of Austria-Hungary in 1914 acted as a catalyst, triggering these alliances and escalating tensions. Nationalism, militarism, and imperial ambitions further fueled rivalries, leading to a large-scale conflict that enveloped multiple countries. The interplay of these factors ultimately set the stage for the war.